Grafana 9 alerts still running for deleted panels

Since I updated to Grafana 9, some of my panels show a blue color alert, and when you try to click on it, an error “unknown alert type” (so you can’t delete the alert). I decided to duplicate the panel, delete the old one and create again the alert, and it seems that after a few attempts, it resolves the blue alert and “unknown” error, but it looks like previous alerts are still running even if the panel has been deleted.

How to handle that?

Also it looks like now we can’t anymore delete “all” the alerts from a panel, how come has that ability been removed or is an alternative way to do it (tried to find it, no luck)?