9. (1) A public servant may opt to retire from service at any time after he has completed twenty-five years of service by giving notice in writing to the appointing authority at least thirty days prior to the date of his intended retirement : Provided that such option once exercised shall be final and shall not be permitted to be modified or withdrawn. ¹[(2) The Government may, if it considers necessary in the public interest so to do, retire from service a public servant at any time after he has competed twenty-five years of service without assigning any reason.]