23.—(1) The licensing authority may revoke—
(a)an appointment made under 22(1)(a), or
(b)an approval given under regulation 21(3) or (4) or 22(3) or (7),
by notice in writing and the authority of the person whose appointment is revoked or whose approval is withdrawn to conduct theory tests or, as the case may be, to appoint other persons to conduct unitary, practical or theory tests, shall cease upon the date specified in the notice.
(2) Where a person has his appointment revoked or if an approval given in respect of him under regulation 21(3) or 22(3) is withdrawn, that person shall immediately return to the licensing authority all forms of pass certificates supplied to him under regulation 44(8) which he still holds.