how can I uninstall a program

Generally there are three ways to do it.

1. Check with the app developers to see if they have a utility to uninstall their app, do this first.
2. Drag the app to the Trash and then empty the Trash.
3. You can use a third party app tool such as App Cleaner to uninstall apps.

Almost always, I use #2.

You also should refer to How to uninstall apps on your Mac - Apple Support

What program?