Simpy drag & drop the LW application folder into the trash. Other items you could get rid of is the LW receipts package found in the Library/Receipts folder, however you might not necessarily have one since the new version LW doesn't seem to create one. Also Preferences folder found in Users/Your Account/Library/Preferences/LW Prefs. Deleting LW Preferences folder in OSX

Other than that, there is your download folder & incomplete folder, which will be wherever you located it at. Perhaps within your user account.

"MUST" uninstall LW? I'd like to know the reasoning. Most likely someone who has never in their life used a p2p sharing program, so can't exactly be called a genius. Just someone with an attitude. The fact he had no idea how to uninstall it says a lot. Most programs on Mac OSX are uninstalled the same way. So sounds like that person does not know much at all.