Actually, sites followed by users remain on SharePoint Online landing page after site been deleted. It works for standard sites as well for teams sites. Is any chance to enable auto-removal sites from favourites and landing page after site will be deleted? I got several questions for this functionality during my training and consulting work.

There is a resolution explained by Quin Tang from MSFT here in this thread: {http://bit.ly/SPODelFav} but it's additional work for SharePoint admin.