Section 279(4) in The New Delhi Municipal Council Act, 1994
(4)Where an order of demolition of building under this section has been made, the owner of the building or any other person having an interest therein, shall demolish that building within the time specified in that behalf by the order, and if the building is not demolished within that time, the Chairperson shall demolish or cause to be demolished the building and sell the materials thereof.