Deleting and Blocking Friends
Block a User
To Block a user who added you, tap "Added Me" on the Profile Screen:
Tap their name and press the gear icon that appears next to their name.
Press Block to prevent them from sending you Snaps or Chats or from viewing your Stories.
Press Delete to remove them from your friends list.
Unblock a User
To unblock a user, tap the Settings gear on the upper-right corner of the Profile screen. Tap "Blocked" under the Account Actions at the bottom of the Settings screen
You will see a list of the users you have blocked. Tap the 'X' next to their name to unblock them.