Section 56(1)(b) in The Gujarat Housing Board Act, 1961
(b)that any person is in unauthorised occupation of any Board premises, the competent authority may, notwithstanding anything contained in any law for the time being in force, by notice served (i) by post, or (ii) by affixing a copy of it on the outer door or some other conspicuous part of such premises, or (iii) in such other manner as may be prescribed, order that that person as well as any other person who may be in occupation of the whole or any part of the premises, shall vacate them within one month of the date of the service of the notice.