It is possible to revoke (cancel) a Living Will at any time while you still have capacity to do so.
A cancellation of an advance statement in terms of the Mental Health (Care and Treatment) (Scotland) Act 2003 has to be in writing and comply with the same formalities that apply to making an advance statement.
There is no legal framework for creating an advance directive and so no framework for cancelling one. To avoid the risk that the relevant people do not know you have cancelled your Living Will, it is advisable to put the cancellation in writing, and to inform everyone who was aware of the decision's existence.
After you have revoked your Living Will, you should destroy the original document, or mark on it that it has been withdrawn.