You signed a contract; therefore, you are obligated to sell and if you refuse to, the buyer could sue you in court and get a court order compelling you to sell (called "specific performance") and also potentially get monetary compensation from you, too. Once you contractually agree to something, you cannot simply decide you don't want to do that thing.You can only escape the contract if:1) The buyer lied to you about something important to get you to sign (fraud);2) The buyer violates some important obligation of his in the contract, like not paying some deposit or other amount when due (breach of contract);3) The contract itself contains some early termination or cancellation clause allowing you out of it, and you 100% comply with the terms of that provision.