Watching Crunchyroll's releases through Grayjay, if I follow a series as I would subscribe to an Youtube channel (they're treated as the same by Grayjay), they appear in the subscriptions and can be hidden by toggling off the default filter "watched". Also, you can generate a playlist of a series' episodes, and remove each episode as you watch them.

Grayjay's Crunchyroll integration only works if you log in to Crunchyroll and have access to the episodes, though.