Section 51(6)(b) in Sikkim Urban and Regional Planning and Development Act, 1998
(b)(i)In the case of the notice requiring the demolition or alternation of any building or works or carrying out of any building or any other operations, itself cause the restoration of he land to its condition before the development took place and secure the compliance with the conditions of the permission or with the permission as modified, by taking such steps as the Authority may consider necessary including demolition or alteration of any building or works or carrying out of any building or other operations;(ii)The authority may recover the cost of any expenses incurred by it in this regard from the owner as arrears of land revenue.