If the application came with an installer then, on rare occasions, you can run the installer to uninstall or run a separate un-installer...
Most of the times this is completely unnecessary, though, as almost every Mac app can be uninstalled by dragging the app to the trash and empty (when the app isn't running...)
If you want to clean out the preferences too, search (or browse ~/Library or ~/Library/Preferences) for any files called whatever the app is called and delete those too...
And try searching the forums next time you have a question, as this and most other questions have been answered more than once before... 😉