C9 can't seem to find option to delete containers?

I was experimenting with layout and added a 2 column container. Now I can’t delete it - it’s driving me crazy! It has no blocks in it, it’s just sat there doing nothing, and I can’t find any options to delete it in any of the menus. What am I missing?

Click ‘Edit Container Layout’, then click the ‘Bin’ icon, then click ‘Delete’.