Or I could use this awesome app called AppCleaner. But, what if I didn't discover App Cleaner until recently.
In most cases, app removal software like AppCleaner doesn't do a thorough job of finding and removing files/folders related to deleted apps. For more information, read
this and
this. If you just want to delete the app, drag the .app file to the trash. No other software needed. If you want to completely remove all associated files/folders, no removal apps will do the job.
I guess I'll have to wait until I do a clean install when I get my external hard drive before I can clean it out.
You can still use the manual method in the link I posted to remove app-related files from apps you've already deleted, as long as you remember the app names.