At any time and until the expiry of a period of fifteen days from the date on which the decision has become res judicata, the tenant who has made a request in accordance with articles L. 145-47, L. 145-48 or L. 145-49 may waive it by notifying the lessor by extrajudicial act or by registered letter with acknowledgement of receipt, in which case the lessor shall bear all the costs of the proceedings.