Open Messenger
Open the chat with the person you want to block
Tap their name at the top
Tap Block
Choose Block on Messenger
Confirm the block
On iPhone or Android:
Open Messenger
Tap your profile picture
Tap Privacy and safety
Tap Blocked accounts
Tap Add someone
Search for the person
Tap Block
On desktop:
Open Messenger in a browser
Open the chat with the person
Click the person’s name
Click Block
Confirm the block
To unblock someone:
Open Messenger
Tap your profile picture
Tap Privacy and safety
Tap Blocked accounts
Select the person
Tap Unblock