I was yesterday years old when I found out you can recycle used braid hair. I'm not suggesting take your hair down and use the hair again because that's lowkey insane! There a site called Rebundle that will take that hair off your hands so it doesn't end up in a landfill!
They keep the concept simple, take down your braids, visit the site for shipping information and send it off. As long as it doesn't have a weft attached to it they'll take it. You don't have to do anything extra or special, take it down and ship it off!