I used to uninstall them by hand (i.e. dragging the app to the trash) in the pre-OS X days, it was a pretty simple procedure. I did this too in my early OS X days but found some
orphaned files here and there.
Being a neatness freak (and not liking the thought of having files that just sit there for nothing in the prefs folder and Application Support folder, I tried
AppZapper and have used nothing but, since then. Very decently priced for the work it does. :girl:
Some programs DO need their own uninstaller though.
If you have the time and patience, you also can do a Spotlight search for all the pieces but sometimes the files use the program's name, sometimes in certain spots they will take on the software company name not to mention that by manually deleting files, you can erase a file you actually need for other programs...