Old TiVo boxes - How to remove from online and local TiVo box list?

How do I remove unplugged TiVos for the box list of my other networked TiVos? The removed TiVos are still active with TiVo but unplugged so they have not called home in weeks. I now have 5 TiVos listed under box online and under each TiVo. I want to "delete" 2 of then.

Old TiVo boxes - How to remove from online and local TiVo box list?