Mobile:
First, you have to log in Facebook:
And then, tap here and go to Blocking tab:
Next, tap Blocking
On Block User ~> User name (here I unblock Mishra Rupesh) ~> Unblock:
Next, tap Unblock:
I unblocked Mishra Rupesh success:
Desktop:
First, you have to log in Facebook:
And then, click here and go to Blocking tab:
Choose Block User ~> User name (Molie Handley) ~> Unblock:
Next, Confirm:
Done.