Mortgages may be discharged by an entry on the margin of the record thereof in the record of deeds, acknowledging satisfaction of the mortgage, signed by the mortgagee or by his or her executor, administrator, assignee, attorney at law, or attorney acting under a duly executed and recorded power of attorney, such signature to be witnessed by the town clerk or assistant town clerk having custody of such record. Such entry shall have the same effect as a deed of release acknowledged and recorded.