Unless you are switching from Nvidia to AMD (ATI) or vice versa it's usually enough uninstall from the Control Panels Add/Remove Programs section, although I, as others do, just install 'over the top', which upgrades the software while keeping the old files available for a rollback should things go pear shaped.
OR...
Set a Restore Point.
Download and install DriverSweeper.
Uninstall the existing software.
Reboot into Safe Mode.
Run Driver Sweeper.
BE VERY CAREFUL! Check every file it is going to delete, it has been known for programs of this type to delete importaint system files (which is why you should set a Restore Point
)
Reboot normally and install the new software .