Not a bad idea. Sherlock Holmes believed in it.

In "A Study in Scarlet," Dr. Watson expresses surprise that Holmes is ignorant of Copernican theory and the composition of the solar system. Holmes explains that he does his best to forget any information that is not relevant to his existence.

Now, is it good that I remember that trivia -- or should it have been eliminated as clutter?

Then there's the Bucket Theory. Your mind is like a bucket, and every new thing you learn fills it up, until your bucket is so full that learning a new thing will make you forget something you already knew; it just leaks out of the bucket. This is why nuclear physicists can't find their car keys (for example).

This is also an argument against learning too many things, since nobody can be sure if they have a big bucket or a little bucket. It's why I don't learn anything at work that I don't absolutely have to know; I don't want my bucket filling up with that stuff when I could be learning interesting things instead. Also, I might have a little bucket, so why take chances?