You have to put it back in the place in the guild it came from. Find a player guildmaster to reinstate you, pay the bribe to get your password back if you have forgotten it, its pretty cheap these days.

Alternatively, it might be possible to get a throwaway container from a general store, put the burlap bag in that container, and throw the container away. I don't know if that would break guild stuff though, but it is a way I've had to use to get rid of another item that has similar scripts preventing it being thrown away.