The Act Schedule 1: Safety directions Paragraph 10
17.The Secretary of State can vary or cancel (revoke) a direction and is obliged to do so, as soon as reasonably practicable, once a direction or part of a direction is no longer necessary for the purpose for which it was given. The person to whom the direction is given has the opportunity to make representations about varying or revoking the direction, which the Secretary of State will then consider.