Section 18. A conservator may be discharged by the probate court upon the application of the ward, or otherwise, when it appears that the conservatorship is no longer necessary. But a conservator of the property of a married person shall not be discharged without such notice as the court may order to the husband or wife of such person. In the event of the death, resignation or removal of a conservator, the court, on the application of the former ward and after notice to his heirs apparent or presumptive, including the husband or wife, if any, may certify that the said ward is discharged by operation of law, and if it so appears, that conservatorship of the property of said ward is no longer necessary.