If you've granted a General Power of Attorney (GPA) for a plot of land to your father-in-law, you may be concerned about his ability to sell it or take out loans against it. The good news is that you can cancel a GPA at any time. To do this, you'll need to execute a deed of revocation and register it at the sub-registrar's office, followed by sending a copy to the agent via registered post. Some advice suggests approaching a civil court for cancellation and sending a legal notice beforehand.