Let it Dry
Don’t try to remove stuck play dough while it’s still soft. It’s important to let it dry completely. Then, use a stiff-bristled brush to remove as much of it as you can. A grout brush will work best, and you should be able to find a quality one at Hardware World, but a toothbrush may do the trick.
Once you’ve scrubbed off as much of the dried play dough as you can, soak the stained section in a cool bowl of water with a few drops of dish soap for around 30 minutes. This step causes the dough to release its grip on the clothing fibers.