Notice in writing must be given to the occupant or owner of the land, or person causing or owning the encroachment, either personally or by mail, postage prepaid, addressed to the owner, occupant or person causing or owning the encroachment, at the last known post office address as disclosed by the County Assessor, said notice to specify the width of the street between the property lines in front of the encroachment, the place and extent of the encroachment, and requiring such person to remove the same within ten (10) days thereafter.