you can ignore it if it isn’t a court mandated order. the lawyer wants to be paid, but they don’t need to be paid by OOP. they’re perfectly fine being paid by the harassing neighbor, which is what will happen eventually. there are always some of these harassment cases, and generally they go away if you just ignore them because there is no legal backing. the lawyer just scares you into compliance and if you pay that gets seen as an admission of guilt. there are several types of legal letters but most of them don’t require responding at all.