The short answer is that the terms of the contract, presuming it is a written agreement and not an oral one, will determine whether you are able to prematurely terminate the contract without further liability. Without actually seeing the contract, I would suggest:
Pay specific attention to the provisions dealing with the "term," "termination" or "early termination." Depending on your contract, you may be required to pay the remaining obligation under the contract or an early termination penalty.
If you believe the other party has not fulfilled their end of the contract, or you believe the other party is "in breach," you may have the right to terminate the contract by providing written notice to the other party. However, again, depending on what the contract says, the other party may have an opportunity to "cure" the defect or breach.
I would suggest you consult an attorney to review the terms of your contract and advise you accordingly.