White Out or any correction fluid leaves a very nasty stain. It is very similar to paint stains, but also has characteristics of plaster stains because of its thick consistancy. Once it has dried in place, you will have to use a putty knife to remove the majority of it. To remove the remaining residue, use paint thinner on a clean rag. Work the thinner into the stain until it begins to break down. Use a clean part of the rag and fresh thinner to remove the remainder. Be very careful when using paint thinner, it will discolor many surfaces. Also, it will obviously remove any paint from the area you are trying to clean. Paint thinner is also flammible and exposure can be dangerous, so always wear gloves and a respirator.
