Plastic screw anchors are useful when hanging a variety of objects, such as mirrors, pictures and even lightweight shelves. The most common plastic screw anchors are the simple plastic expansion anchor and the plastic threaded anchor. While their installation is basic, removal of the anchors is tricky and may result in excessive damage to the wall. Thus, when extracting plastic anchors out of walls, it is best to take your time and work carefully.
Thread a long screw partially into the plastic anchor. Turn the screw just far enough so that it starts into the first section of the anchor. Do not thread the screw all the way into the anchor, as this will cause the anchor expand. If the anchor expands, it will be more difficult to remove or will create a large hole in the wall when you pull it free.
Grasp the head of the screw with your fingers and gently wiggle it as you pull. Be patient and work slowly, as the anchor will be tough to remove at first. Work the screw from side to side and continue to pull outward. Eventually, the anchor will pull from the wall. Remove all expansion anchors using the same technique.
Apply patching plaster to the hole in the wall. Allow the plaster to dry, sand smooth and paint.
Insert the head of a screwdriver into the anchor. Choose a screwdriver that is small enough to fit through the hole in the wall and the open end of the anchor.
Turn the screwdriver counterclockwise. As you turn the screwdriver, the anchor will begin to emerge from the wall. Continue turning the anchor until you've fully removed it from the wall.
Apply patching plaster to the hole left in the wall. Allow the plaster to fully dry, sand smooth and paint to match the surrounding wall.
Some expansion anchors will prove nearly impossible to remove without creating a large hole in the wall. In this case, position a razor blade flat against the wall, directly above the anchor. Slide the razor blade downward until the cutting edge is against the plastic face of the anchor. Carefully, push down and work the razor blade from side to side until you severe the face of the anchor. With the face removed, use small awl or screwdriver to push the anchor deeper into the wall. Cover the remaining hole with plaster, then sand and paint the area.