I hired a property management company to manage my house and moved out of state. Since then, they don't respond to the tenants problems and then they call me and I take care of it and I have received 1 check that bounced and they claimed they switched accounts in the middle of the transaction and they deposited another check to cover the bounced check with the bounce check fee. That check just bounced too. I want to fire then. How can I accomplish this?

If you desire to have someone else manage the property, arrange that first. Consider terms in the contract which will make clear their duties and obligations.

Then, assuming nothing to the contrary in the written contract you have with them, write them a letter to the effect that you no longer requre their services, and instructing them to turn over keys, etc. to the new company.