Note: you can not permanently delete an entire wall from your project, you can only remove (hide) it.
To remove one of the room walls, you need to tap on it first. Then use the Hide button. That way, the wall will no longer be visible on your plan. But if you want to get it back, use the same algorithm: pick the wall and click Unhide icon.
If you would like to hide the wall between two rooms, you need to:
Choose the wall you'd like to be not visible in the first room and hide it.
Click on the second room.
Do the same with the wall you want to hide.
If you want to create a passage between two rooms, here's what you need to do:
Choose the wall of the first room and click on the icon to create an additional point on the wall.
Then, do it one more time, and place two dots on the desired locations.
Hide the wall between these dots.
Click on the second room and do the same with the remaining wall.
