N.H. Rev. Stat. Ann. § 147:4

The health officers may notify the owner or occupant of any building, vessel, premises, or property to remove or destroy any nuisance or other thing therein deemed by them, on examination, to be injurious to the public health, within a time limited; and in case the owner or occupant, after such notice in writing, given to the owner or occupant or left at the owner's or occupant's abode, shall neglect to comply with the order, the health officers may forcibly enter and cause the nuisance or other thing to be removed or destroyed.