First of all, you can rebuild your LaunchServiceDatabase using this terminal command:
/System/Library/Frameworks/ApplicationServices.framework/\
Frameworks/LaunchServices.framework/Support/lsregister \
-kill -r -domain local -domain system -domain user
this will eliminate any duplicates and/or apps that are no longer installed.
Then, if you are good with a text editor, you could edit that same database to remove unwanted apps, or check versiontracker to get a utility to do it 🙂