then if you are a perfectionist .. empty the trash ..
and there may be preference files you can trash. it does not hurt anything if you leave them where they are, but you can delete them too.
User (whatever your username/home is) / Library / Preferences
Look for files that have something about the program you trash. E.g. trashing Internet Explorer > look for files that have explorer, so you'll trash e.g. com.microsoft.explorer.plist -file.
Leaving them there hurts nothing. It is just the perfectionist in you that may want them deleted. .. and you are done.