Remove the screw from the anchor
Grip the anchor with needle-nose pliers
Pull the anchor straight out if it is loose
Twist the anchor gently while pulling if it resists
Use a flathead screwdriver to pry the anchor out if needed
Push the anchor into the wall if it will not come out cleanly
Patch the hole with spackle or joint compound
Sand the patched area smooth after it dries
Prime and paint the repaired spot to match the wall