To unfriend someone on Facebook, follow these steps:

1. Open the Facebook app on your phone or tablet.
2. Search for the person you want to unfriend by entering their name in the search bar.
3. Go to that person's profile.
4. Tap the "Friends" button on their profile.
5. Select "Unfriend" from the menu that appears.
6. Confirm by tapping "OK" or "Confirm" to remove them from your friends list.

After this, the "Friends" button will change to "Add Friend," indicating you are no longer friends with that person on Facebook