'Ghost' Entries in Favorites

Sonoma 14.5 - latest production - M1 chip MacBookPro - 16inch

I had an email account with a folder that I had added as. favorite.

I deleted the email account - and the favorite sits there - unmoved by anything I do. Not active, wont delete.

I reconnected the old account - and tried to delete. Nothing.

I have assumed that there is a plist somewhere that lists the favorites - but cannot find it anywhere.

Does anybody know how to fix please.

I also have an incorrect 'Unread Mails' count ... 22) that I also cant seem to flush.

Slowly my favorites are heading towards ghosts and errors rather than something of use.