Sometimes, the same properties that make a product useful in one set of circumstances can make it irritating in another. Water-based acrylic paint, for example, is waterproof when dry and resistant to being removed. If you accidentally spilled some fresh paint or want to remove some old acrylic base and apply a fresh coat, use one of several standard methods to remove acrylic paint.
You can remove acrylic paint from a small item by soaking it in liquid laundry detergent (any kind) for anywhere from 20 minutes to 1 hour -- depending on the thickness of the paint. The detergent will break down the acrylic, making it soft and pliable as it starts to revert to a liquid. This is an effective way to remove dried-on paint from paintbrushes that would otherwise be ruined; the detergent will soften the paint enough so you can wash it away -- or at least peel it off the bristles -- without damaging the brush itself. You can also use this method for things like clothing and carpeting that have thick acrylic paint stuck to them. Do not dilute the detergent; use it full strength for best results.
Remove acrylic paint from a hard, strong surface, such as brick or concrete, using a heavy-duty scrub brush along with soapy detergent water (about one part detergent to 30 parts water). In some cases, a plastic scrub brush will be enough, but if the paint proves particularly thick or tough, try a brush with metal bristles. Use a circular motion when scrubbing and be patient; it may take a while to wear down the paint.
If you're lucky enough to have acrylic paint stuck to a hard, non-porous surface such as glass, ceramic or metal, you can usually peel it away with your fingers. If the paint has adhered so strongly to the surface that peeling proves impossible, use a sharp utility knife or straight razor to help scrape the paint away. Even using this method, however, the paint usually comes off in large strips.
Paint stripper will remove acrylic paint from surfaces like wood, concrete or any material robust enough to not suffer damage from the stripper. Don't use it on surfaces with dyes or paints beneath the acrylic that you want to preserve. Use a gel stripper on vertical or uneven surfaces for best results, since it will stick where you put it. Leave the stripper in place for as long as the manufacturer recommends, then scrape with a metal paint scraper. You may need to apply more stripper and scrape multiple times to remove the paint. If stripping paint from wood, you might need to finish by scrubbing or sanding to remove the final traces.