N.H. Rev. Stat. Ann. § 230:55

Whenever the commissioner of transportation shall alter or relocate any portion of any class I or class II highway, and finds that there is no further occasion to use such portion for class I or class II highway purposes for property acquired by the state in 1945 or earlier, the commissioner shall post notice of such finding in 2 public places in the town in which land is situate and give notice in writing to the selectmen of such town. Notwithstanding any provision of law to the contrary, the commissioner may discontinue any right-of-way, or portion thereof, that was laid out by the state and declare property acquired after 1945 as surplus and dispose of it in accordance with RSA 4:39-c.