Real State short sale Seller option to cancel

I’m the seller and the beneficiary in a short sale agreement.

The contract include a trustee and all those terms in a well done short sale contract.

Now I change my mind.I wanna keep my house.

Now to cancel the contract,the trustee wanna get pay.

Do I have to pay him in order to revoke everything ? or I have the right as owner and beneficiary of cancel the agreement on my own.