Can I force a sale? I own 50% of the house and I need out of the property.
While I am not an attorney or real estate expert, I would venture to say you cannot force a sale unless you have an express, written agreement that specifically states either party may elect for the other to participate in a sale under certain circumstances or for no reason at all. You have options to 'get out of' the property.
You could sell your interest in the property to an investor or the other party.
You could leverage your need to 'get out of' the property with the other party to achieve your objection.
Getting rid of the ownership aspect is a no brainer, but I am assuming you need to release yourself from the financial obligation. If you need to unload your obligation you still have options but the methods to execute these options are a bit more complex.
Contact a local real estate attorney.