Open Facebook Messenger
Open the chat with the person you want to block
Tap the person’s name at the top
Tap Block
Select Block on Messenger
Confirm your choice
On the Messenger app, tap your profile picture
Tap Privacy and safety
Tap Blocked accounts
Tap Add someone
Search for the person’s name
Tap Block
On Facebook, open the person’s profile
Tap the three dots
Tap Block
Confirm the block
To unblock someone, go to Blocked accounts
Select the person
Tap Unblock on Messenger or Unblock on Facebook