HUGE hair knot help

My 12 year old apparently hasn’t been brushing her hair after her showers & just tosses it up in a bun. Well, it’s now one giant knot and I have no idea how to get it out. I put a ton of coconut oil in it, not sure where to go from here. This is the worst knot I’ve ever seen. Help please, any suggestions that don’t involve cutting her hair to get it out would be awesome, thanks