To successfully remove an escutcheon (metal or plastic used to add a decorative cover to the pipe holes), you may either pull it out straight or unscrew it.
Carefully inspect the faucet for any wear and tear, considering the O-ring, washer, and valve seat. If evidence of damage is found on any part of these components, be sure to switch out or replace that piece right away.
If the O-ring is damaged, use pliers to remove it and replace it with a new one. If the washer is damaged, remove the screw holding it in place and replace it with a new washer.
Reassemble the faucet components in reverse order. Securely place the faucet stem back into its socket and firmly tighten the nut that holds it together.