Open the Facebook profile you want to block
Tap the three dots menu
Select Block
Confirm by tapping Block again
To block from the Facebook app, go to Settings and privacy
Tap Settings
Tap Blocking
Tap Add to blocked list
Enter the person’s name
Select the correct profile
Tap Block
Confirm the block
To block from Messenger, open the chat
Tap the person’s name at the top
Tap Block
Choose Block on Facebook
Confirm the action