Questions are like titles.
Solution: first enter exit to exit. Then you can enter the bios through F2 to solve it, or you can choose to enter windows through F12 first. Then install DiskGenius
The operation is shown in the figure below
Just delete the ubuntu startup item
References
How to manage UEFI boot items under Windows? easy to use method
Teach you to completely uninstall Ubuntu dual system, decontamination without residue