IF IT IS A NEW TENANT, I PERSONALLY WOULD FIND A NEW TENANT. IF IT IS A RENEWAL, WE BOTH NEED TO BE HAPPY, SO WE WOULD NEGOTIATE UNTIL WE COME TO TERMS. IF WE CANNOT, THEY WILL HAVE TO FIND A NEW PLACE. I AM AN AGENT AND A LANDLORD, I AM THE LORD OF THE LAND, PERIOD.
Hello, if the tenant doesn't want to sign the lease then you must inform him or her that you will have to give them notice to move out or if they do not move you may have to file papers in court for eviction. If they want something changed its up to you to agree to those terms or not.
Since I don't know the details you may have to seek an attorney for advice. Good luck!