I found how to remove a listing from 'owned' movies, but how do I remove a movie from the database completely? I only want to list what movies I physically own.
The database is an encyclopedia of movies, and you can't remove movies from it.
You can just superimpose your personal information on the encyclopedia: whether you own videos of a movie, whether you like an actor or not, etc... Then you can use the "criterion search" to filter and list only the movies you physically own. That's just an example. Using more criteria, you could have listed "the excellent westerns that you own", etc...
Did you find the criterion search ? You have to make appear the movie search, then click the tab "criterion search".