Pure acetone is the only way, don't pry them off it takes layers of your natural nails making them very week or damaged. Being a licensed nail tech, you can heat the acetone to a warm temperature in the microwave (being very careful) put your hands in the solution with a towel layed over your hands keeping the warmth in and play with your fingertips while summersed until they desolve. When your done get a buffing block like they use at the shop and buff off anything remaining. Good luck!!!
I got them put on for grad, expecting them to last a month, while they lasted for 4 months. The only say that they finally came off was soaking them in nail polish remover, and slowly prying them off. You can also go to the nail salon and pay to get them removed.