The simple answer is NO. You rented the property to the end of July and you are bound, exactly as the tenant would be.
The response given is not intended to create, nor does it create an ongoing duty to respond to questions. The response does not form an attorney-client relationship, nor is it intended to be anything other than the educated opinion of the author. It should not be relied upon as legal advice. The response given is based upon the limited facts provided by the person asking the question. To the extent additional or different facts exist, the response might possibly change. Attorney is licensed to practice law only in the Commonwealth of Pennsylvania. Responses are based solely on Pennsylvania law unless stated otherwise.
The more complex answer is "it depends" on the terms of the contract. There are lots of provisions in a contracts that often make them void or voidable. For instance, a contract is void for public policy reasons if it is for an illegal purpose. There are many many reasons that a contract can be void. There may also be defenses to a contract, such as capacity. One must be of sound mind and age to enter a contract. There must not be Fraud. These types are arguements can cause the lease to be disolved depending on the circumstances of the parties and the terms of the lease. I recommend that you contact a real estate attorney or contract attorney to discuss these options in more detail.
In Colorado, there are specific terms, which can cause a contract to be illusory (non-enforced) or to be in violation of Colorado's public policy.