At this point it is better to allow the paint more time to cure and adhere to the old paint. Some paints can take several days, even 2 weeks, before good adhesion is achieved.
If removal is necessary you can try wiping it down with hot water and soap, dish soap will work. A harsher cleaner like TSP (Trisodium Phosphate) can be used. This could remove more paint easier when compared to a mild soap. The key is using hot water.