If you can't remove the application using the usual way, then use the information presented below. Type CMD + Space and start the Terminal. Use su root and type your keychain password.
Next type mdfind -name "application name" and input the application name. Once you have found the paths type rm -rif PATH. The usual path is ~/Applications/[Application] so the rm command will look like
rm -rf ~/Applications/[ApplicationNAME].
Reboot your Mac and that's it. The application has been force-uninstalled.