Ukerin

For the record, demolishing and rebuilding does work to downgrade to level 1 (CTRL+Right Click after demolition complete, where demolish was, there is an option to rebuild as a level 1) or even level 0 (for 0, you have to CTRL+Right Click while it is still exploding; this may be only available after demo to level 1, I didn't test without going to 1 first). However, as soon as you enter and leave the Tracking Station (at least), it will automatically revert all buildings to fully upgraded again.