[Windows+Ubuntu dual system]
1. Completely delete the Ubuntu system
windows+R enter cmd
Then enter diskpart and the popup will pop up:
Enter list disk
The computer I am currently using: Disk 0 is a solid-state drive, Disk 1 is a mechanical hard drive, and Disk 2 is a solid-state drive connected to a hard drive and
Both my windows system and ubuntu system are installed on disk 0 of the solid state drive.
Next enter select disk 0
Enter list partition
As shown in the figure above, the type is found as unknown
These unknown types of partitions are the partitions currently used by my computer to install the ubuntu system.
Then delete them one by one
Select select partition 6
deletedelete partition override
In the same way, continue to delete partitions 789
Select select partition 7
deletedelete partition override
Select select partition 8
deletedelete partition override
Select select partition 9
deletedelete partition override
The above deletion is completed.
2. Delete the startup items of Ubuntu system
Here I introduce two methods to delete Ubuntu startup items:
Although the partition of the Ubuntu system is deleted above, its startup items are not deleted. Failure to delete the startup items may cause trouble that Ubuntu is still booted but cannot enter the Ubuntu system after booting. The following is the operation of deleting its boot items;
windows+R enter cmd
Enter diskpart
list disk
select disk 0 (disk 0 is the disk installed by the windows system)
list partition
The drive letter cannot be the same as an existing drive letter. For example, if your computer already has a CDE drive, then allocate the letters F, G, H, etc. that come after E among the 26 letters. It is best to separate them by a few letters to prevent you from plugging them in. USB sticks and drives.
select partition 1
assign letter=J
The drive letter J just assigned will appear.
Due to insufficient permissions, the disk cannot be opened directly. It can be opened indirectly through Notepad. In the Windows attachment, run Notepad with administrator rights.
After opening Notepad, go to [File] -> [Open] in the upper left corner, select the J drive you just added, and you will see an EFI folder inside
Go into the EFI folder and delete the Ubuntu folder
(If the above still cannot be deleted, you can use the administrator user to log in to the computer, then enter Disk J to find the Ubuntu folder and delete it)
How to open the administrator user:
Method 1: Press the Win+X key combination or right-click the start button to run the command prompt window as an administrator and enter the following command: net user administrator /active:yes
Method 2: Press the Win+X key combination or right-click the Win10 start button to pop up the system shortcut menu and select "Computer Management".
Open the "Computer Management" window, click "System Tools - Local Users and Groups - Users" on the left, and then you can see the Administrator account in the right window.
Right-click the Administrator account and select "Properties" to open the "Administrator Properties" window.
Uncheck the box next to "Account is disabled" and click OK to close the window.
After the above problem is solved, return to the non-administrator user to continue the operation:
Return to the command line just now and delete the drive letter just assigned. It can be seen that it has returned to its original state
remove letter=J
Since then, the ubuntu system has been completely deleted.
Start installing the Ubuntu system:
1. Make ubuntu USB boot disk:
Download Rufus 
Rufus - Easily create a USB boot disk
Download the ubuntu image file Ubuntu 20.04.6 LTS (Focal Fossa)
The disk creation tools and system image files are ready
First, you need a U disk of about 8G
Format as follows
1. win+r to run and enter cmd
2. Enter diskpart in the command prompt window
3. In the pop-up DISKPART window, enter "list disk" and press Enter. The hard disk and U disk on the computer will be displayed. Based on the size of the disk space, it can be inferred that disk 2 is an SD card.
4. Then execute the following commands in sequence
SELECT DISK 2: Select disk 2 ( do not select the wrong disk ).
CLEAN: Delete the entire disk data.
CREATE PARTITION PRIMARY: Create a primary disk partition.
ACTIVE: Activate the disk partition.
FORMAT QUICK: Quickly format the disk partition.
Since then, the U disk has been formatted
Start making Ubuntu U disk boot disk
1. Find Disk Management
Open rufus (double-click directly)
Start burning the system
Next, keep the default option
Next, enter the computer's BIOS according to different computers.
Taking the computer you are currently using as an example, keep pressing F2 when turning on the computer to enter the BIOS interface and select boot for settings.
Then press F10 to save. The computer will automatically restart. During the restart, we keep pressing F12 to enter the Boot Manager interface.
Start entering the Ubuntu system
Pay attention next
Find the system disk of your computer, your solid state drive, and reserve the disk space to install the Ubuntu system in the Install picture above.
The Device display is free space, and the size must correspond to the disk space you reserved, and then select it to operate.
Start partitioning
/boot (ext4 format) (size: 1024 1G)
bios （size: 2048 2G）
swap (swap format) (size: 10240 10G)
/ (ext4 format) (size: all remaining space)
After mounting the partition, the last step is to select the disk for installation and booting, which is to select your system disk.
After entering the Ubuntu system, start changing the domestic source
cd /etc/apt
sudo mv source.list source.list.bak
vi source.list
Add the following:
deb http://mirrors.aliyun.com/ubuntu/ focal main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ focal main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ focal-proposed main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ focal-proposed main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse
By default, the computer enters the windows system by default.
If you want to enter ubuntu after shutting down the computer
Start up and press F12 to enter
