Delete serie in Sonarr when no episodes are left

[Old-T]

Is your feature request related to a problem? Please describe.
Background: I always delete an episode that's been watched.

I try to accomplish to following:
When a Serie in Sonarr is marked as ended and unmonitored, I want to delete the series when all episodes are removed (i.e. watched).

I don't know if this is possible to do since Maintainerr is "based" on Plex libraries. When there are no more episodes left in the series in Plex, it doesn't exist in Plex any longer.

[BaukeZwart]

The only way I managed to do this is by deleting the series before the last episode is deleted. I set the number of days to delete an episode higher than the series delete filter.