Originally posted by Jaggid Edje:

Yah, that one does require the forge. It's a work bench upgrade, but a forge is needed to construct (and deconstruct) it. It also has to be 'near' a forge when placed.

Regardless, busting it with an axe works too. :)
I had the same thing happen a few days ago when I tore down a chunk of my original base to relocate stuff.

Ah ok that makes sense. I´m also rebuilding my house right now which is why I already had deconstructed the smithy.