How do I clear the rubble in the Castle

Question

I'm trying to gain access to the Castle Armory, but I'm stuck at the point where I need to clear the rubble from the tunnel leading to the armory.

Ronnie Shaw suggested I use explosives, I tried throwing a few grenades at the tunnel, but that didn't work. Firing a nuke in that small room also doesn't look like a good idea. The quest marker is on the Workbench, so I guess I'm supposed to craft explosives somehow.

How exactly do I clear the rubble there?

Answer 1

Enter Workshop mode and scrap the rubble blocking the entrance.

Answer 2

here's a video on how to do it for those who like are more graphically inclined.