DIY - Is it oil based, or latex paints? 
Knowing the paint type on your wall is very important as you are projects! Here's my breakdown on how to tell the type of paint previously used on your walls: click here
You likely have these on hand anyways, but this is the main tool you'll need for this project!
You may have nail polish remover on hand, but many no longer contain acetone. That's the main ingredient you're looking for so pay close attention! This option is 98% acetone and will work lovely.