Need help removing icons and priority numbers

Here's what happen. I was trying to understand how to control the outline levels using ctrl-alt + 1-9 and ctrl-alt + / ,as well as ctrl-/. 

I'm finding these controls to be a bit awkward and not always working as I thought they would. I found highlighting all the outline levels seemed to help. 

While all the levels were highlighted I managed to use the keys cntrl-1 , which set all the outline priority levels to 1. It happened very fast. My question is this: is there an equally fast way to undo this? Or do I need to manually delete each level 1 priority icon manually?