# UFW rules are handled in order.  If you add a deny after
# the allow lines, it will be allowed instead of denied.
sudo ufw insert 1 deny from <ip_address> # deny all access from provided ip_address

# The following allows you to delete rules you previously added in the wrong order
sudo ufw status numbered # list rules with associated numbers
sudo ufw delete <serial_number> # delete specific number item.  Will be prompted to confirm