Click on "Uninstall" then follow the prompts as shown below.

Uninstall "MT4ProfessionalSetupMT4" and  "MT4ProfessionalSetupMT5" (if you have installed the MT5 version) via the windows uninstall tool.

In Windows 10 you can search for the app in "Apps & features" and click uninstall

or you can use the classic way via control panel (uninstall a program).

The following window will open

for each MT4 instance where you have installed MT4Professional, you have to confirm whether you want to keep MT4Professional there or not. If you click "no" for that instance MT4Professionall will continue to work properly.