(a) Any owner of all or a portion of land that has been designated a residential planned unit development under this article can apply to the city for the termination of that portion of a stage within an approved final development plan within which his property is located if construction has not been commenced pursuant to the final development plan. The procedure for termination shall be that applicable to a land use classification change under this chapter.

(b) Failure of the developer to submit a final development plan for the entire development or a stage within the time periods specified in section 110-421 shall automatically revoke approval of the complete preliminary development plan filed under section 110-422 and the site shall revert to the previous zoning classification and the official zoning map shall be changed accordingly to reflect such revocation.