Summary:
When I build a house and make a mistake, I sometimes want to delete walls from the plan. But I can’t. Instead I have to delete the whole house and start again. And that’s really annoying.
You can not “rubber” walls - however, sometimes you can instead CTRL+Z to undo walls.
This is very buggy though, so don’t trust this to work all the time.
From my experience, it depends on a) if you’ve been able to build your entire blueprint as one model or not, and b) how many items you’ve placed since the wall was constructed.
However, I believe the “undo of walls” will be a feature after the current building-editor overhaul. Soon™