As the donor if you still have capacity and you decide that you no longer want to have your current advance decision; this could be because you feel that this document no longer reflect your wishes. Then you will need to destroy the document and have a new one drafted to inline with your new wishes.
To withdraw an advance decision, you can cancel it at any time while you have capacity to do so. There is a formal process, to cancel, you will need to cancel it in writing and should destroy any written document. Tell everyone who knows you have one that you have cancelled it and put this in writing to avoid uncertainty. Healthcare professionals should record any verbal cancellation in your records for future reference.
The reason that we advise that you do this is to save any confusion in the future. Because if you feel that the advance decision no longer reflects your wishes and you have told people that you have changed your mind. And then this document is then shown to your medical professionals. This could course confusion and could delay in your treatment.