Audible Originals are more like Podcasts than AudioBooks. But you’ll notice there is no way to remove them from your mobile app on iPhone and Android. However, there is a way.
To do that, you have to go on the computer to your Amazon Account. Go to Accounts and Lists and then to Manager Your Content and Devices
Once you are there, select to Show Audiobooks from the drop-down and select the Amazon Originals episodes you want to remove and DELETE from your library using the Delete button.
Although, I don’t recommend removing Michele Romanow’s “The Revisionaries”. It is pretty great.
Once you delete, sync your library on your mobile device and the deleted media will go away from your library.
If this helps, please share on your social circles to help your friends.