TLDR: This is a bad idea

If you want to rebuild from the vault door, the only way is to remove all your living quarters and you can only do that if you first evict (or kill) all your dwellers. Including exploring dwellers.

Then you can rebuild. But, and here's the important thing. More dwellers don't just appear like they did when you started.

In theory this situation can be remedied by getting rare dwellers from lunchboxes. But I've opened 3 lunchboxes and no one has appeared...

TLDR: This is a bad idea

If you want to rebuild from the vault door, the only way is to remove all your living quarters and you can only do that if you first evict (or kill) all your dwellers. Including exploring dwellers.

Then you can rebuild. But, and here's the important thing. More dwellers don't just appear like they did when you started.

In theory this situation can be remedied by getting rare dwellers from lunchboxes. But I've opened 3 lunchboxes and no one has appeared...

Edit: After 4 weeks of nothing, I finally got someone from a lunchboxes. They operated the radio room until another came and now I have breeding stock. Game saved!