The last time we had one of those in the barn, we eased a black plastic garbage bag up around it and taped it to the sloping boards of the inner roof. Hubby cut a tiny hole into which he sprayed some Raid for wasps. We taped the hole and left it alone overnight and used a scraper to detach it from the inside of the loft roof the next day, sealing it in the garbage bag. I hope your nest is safely accessible, we were lucky.