I didn't bother replying to this because Gromit's first answer was totally correct.
Apps are stored in /Applications (usually).
To remove an app, you simply drag it to the trash can. That's it!
This keeps little files that store configurations though. Apple leaves these, since they take up so much little room that it doesn't make much difference, and it's useful if you want to get the app back again.
If you want to remove these too, use this app:
http://www.appzapper.com/
(Or a similar one.)