To uninstall Gurobi, open the start menu and type "remove" to find the "Add and remove programs" section. You will find all installed Gurobi versions and you can select which to uninstall.
To uninstall Gurobi using the command-line, please run:
msiexec /x Gurobi-9.0.1-win64.msi
Note, that you need the MSI file for the respective Gurobi version for this operation. You can always get it from our Software Downloads page.