Pour a quarter cup of vinegar into a small vial or container. Place the container near the clothes hook so you aren't juggling too many items at once when you try remove the hook.
Press the bulb of the eyedropper and sink the tip beneath the surface of the vinegar. Release the bulb and fill the eyedropper with vinegar.
Hold a rag against the wall directly under the plastic hook to catch any drips. Touch the tip of the eyedropper to the top of the plastic hook and squeeze vinegar between the hook and the wall.
Wait several minutes and gently pull the top of the hook away from the wall. If it comes partly away or doesn't easily come away from the wall, pick up more vinegar with the eyedropper and squeeze more vinegar behind the hook.
Dampen the rag with the remaining vinegar in the container and wipe away any adhesive remaining on the wall. If the adhesive is resistant, dab the vinegar onto the spot and wait two minutes before wiping it off with the rag. Repeat until the wall is cleaned.