I am living in a house and recently had a falling out with my roommate. When we moved in she was the only one to sign the lease. We agreed that I would move out at the end of the month since I just paid for all of this months rent. After another argument she told me that I have 24hours to leave otherwise she will call the police and have me removed.
Is she allowed to do that? And how do I go about getting my damage deposit back? And if I do have to leave within that 24hours do I not get my money back for the remainder of the month?

No, she cannot give you 24 hours notice. No, she cannot have the police remove you. You are entitled to remain until the end of the month as the two of you agreed. If you don't move out by that date then her only option is to file a lawsuit for eviction.

On the date you move out, make sure you take plenty of pictures to prove there is no damage and make sure you give her your forwarding address in writing. She has 15 to 30 days (depending on your state's law) to return your deposit less the cost of repairing any damage. If she doesn't return your deposit, or a provide a written, detailed accounting of how the deposit was used within that time then you should file a lawsuit.