From the Londonderry Facebook page:

Do you have a flag requiring appropriate disposal? You can properly dispose of your worn or tattered US flag at the Town of Londonderry, New Hampshire Hall just inside the main entrance and during normal business hours (unless Town Hall is unlocked for some other reason like Council Meetings etc).

You can also dispose of your flag at the Londonderry American Legion Post 27 (Sargent Road behind LFD Central) for no charge (either location).

Flag disposal etiquette: https://nationalflagfoundation.org/etiquette/when-to-dispose-of-the-flag/?fbclid=IwAR0OWr3hfhzGvcFpoJjgEfDzgh_w6qL5IDWelTpMouSm4bpfZ9GyRtnoutU

How to properly dispose of worn out American flags: https://www.defense.gov/Explore/Features/Story/Article/2206946/how-to-properly-dispose-of-worn-out-us-flags/fbclid/IwAR2z1Rkj6CM4JYX3DJ-dORQhFgRGzRWrByu7AtP3x854nVEHCMRSqfVB90A/