How do I remove this dashed awkward lines. They appear when I place walls

[briannawi]

[Chopsaw]

Looks to me like they are all invisible walls that are connecting "island rooms" .  You can turn that behaviour off in wall defaults but I think that can cause other problems.  Likely best to just turn off your Walls, Invisible layer when you print.

[mtldesigns]

I do the the same as Eric.  Create a unique layer usually called "Wall, Invisible 2 turn off".. its a couple extra steps you have to do to turn those off, but def. easy to do. 

[Dermot]

Those are added automatically because you have created "island rooms".

 

Here is some more info that might help: