Things happen. You might be friends with someone one day and then not friends the next. If you were foursquare friends, it’s easy to remove that person from your friend list so they won’t be able to see your check-ins (and you won’t be able to see theirs).
There are two ways you can delete a friend on foursquare: through the app or from the website.
In the App
To remove a friend from within the app, simply navigate to their profile. You’ll see a settings icon in the upper right. Tap that and then tap “unfriend” (iPhone) or “remove friend” (Android) on the box that pops up. They’ll be unfriended once you confirm the action.
On the Website
To remove them from the website, navigate to your friends list. Find their name and hover over it. You’ll see a small “X” pop up on the right side. Click that and then confirm your intentions to delete them as a friend.
Turning off Notifications
If you’re just unfriending someone because you’re tired of seeing pop-up notifications every time they check in, you can turn those notifications off for individual users instead of removing them completely. You can do it from the same place. Just tap “Turn Notifications Off” in the app or uncheck the box next to their name on the website. You’ll no longer be notified when they check in nearby.