How do I hide friends or remove them from my friends list?
Go to the Friends tab (the silhouette icon) and tap the three-dotted button on the top-right corner and select Edit Friends List. 

You will be able to remove or hide your friends or remove friends from Favorites.

If you hide your friends, they will be removed from your friends list. (You will still receive messages from your hidden friends.) 

If you want to reinstate any hidden friends to your friends list, go to the Friends tab, tap the three-dotted button on the top-right corner and select Manage Friends. 

Go to Hidden Friends and tap the Manage button right next to the friend of your choice and select Reinstate to Friends List.