Clean the area with soap, water and a sponge. Dirt can get in the way of the solvent, requiring multiple solvent applications for full removal.Blow dry the surface and apply the vinyl paint solvent. A good brand to consider is Grog it is 100% biodegradable and odorless and it is easy to apply using only a paintbrush or rag. Then wait for the solvent to begin penetrating and removing the paint. When the paint starts to bubble, the solvent is has fully penetrated and is ready to be cleaned off, this process usually takes 1 to 3 minutes. Scrape off the paint with a plastic putty knife. Wash the area again with soap and water to remove any excess solvent or paint residue.