For in-game friends you have the option to remove or block a friend. Once you block a player, they won’t have the option to request a friendship again, unless you unblock them. Please note that the block expires after 30 days.
For the other friends (from Facebook or Game Center), you have the option to hide those inactive friends.
This means that:
-Hidden players will not show in RSS friends, friends tab, or the “need help” tab
-Hidden players will still appear in the last helper tab
-Hidden friends will appear in the bottom of this tab
-In order for them to appear again, just press the “unhide” button
Followers tab:
-You can easily unfollow players
-Followers can be either removed or blocked. If you block a follower, he won’t be able to follow you again. Please note that the block expires after 30 days.