Use nail polish remover to soften up dried nail polish and remove it from your fleece sweater. The remover you choose needs to be compatible with the fleece type. An acetone remover may be able to rid the sweater of the polish, but if the fleece is wool based, the remover will eat through the fabric as well. If the nail polish is still wet, simply immersing the garment in water will prevent the nail polish from sticking to the fabric.
Place a clean towel between the layers of the sweater.
Soak a cotton pad with non-acetone nail polish remover. Gently blot at the nail polish spot until it is loosened. Depending on the brand, color, and amount of polish, this could take from one to several minutes.
Saturate a cotton pad with water, and blot the area to rinse away the polish remover.
Hand or machine wash the fleece sweater following the manufacturer's directions on the laundry tag.
Test the polish remover in an area that doesn't show, to be sure the fleece is colorfast before you work on the stain.
Use a cotton swab instead of a cotton pad if the polish is in a small area.
Don't machine wash a wool fleece sweater; it should be washed by hand once the nail polish is removed.