When we install SQLSERVER, sometimes there are problems, and when reinstalling, sometimes the installation fails because of the things left over from the last installation, so it is more important to completely delete SQLSERVER. The complete removal method is as follows:
1. Delete it in the control panel.
2. Delete the installation directory folder.
3. Delete the registry.
4. Install windows install clean up to delete all sql related things.
Reinstall after removing.