From that document, it appears both must be done and the product must be registered as well. The point is, it gives the lie to what Dell said.

Not even Microsoft apps necessarily do a proper tidy uninstall - there is usually something left lurking somewhere. Norton products were always renowned for the amount of rubbish they left behind after supposedly being uninstalled.

Have used this tool several times. It gets rid of everything so you can start again. Takes about 5-10mins to run then a reboot.