Currently, you can hide a show from you calendar or progress page. Hiding from watched progress also hides it from your dashboard on deck. Hiding in those 2 places should work for most users.
This topic proposes a “dropped” status for a show. This would hide from the 3 sections mentioned above + add a “dropped” indicator in places such as the show summary page.David commented
This would be excellent - I might stop watching a series after, say, the 3rd season of 7 but to remove it from progress, I need to mark the whole series unwatched. An example would be True Blood where I gave up after season 5 or Elementary mid way through season 4.