Once the Purchase Agreement is signed by both parties, the only way to cancel it is if the seller agrees out of the kindness of their heart or if one of the contingencies isn’t met. For instance, if the building doesn’t appraise appropriately, and you can’t get a mortgage, you can back out of the transaction. But if you simply decide you don’t like the color of the building exterior, you can’t cancel the agreement. Plus, the seller can sue you to force you to hold up your end of the transaction.