From there you should be able to either resume the draft or delete it. (The delete icon is in the bottom right and is a little obscured because of the colors.) If you resume a draft, you can also pick “cancel”, which gives you an option to delete the draft.
I had five drafts or so saved at one point because I couldn’t post them. When I went to post the drafts, if I got the whirly circle instead of the post, the draft was actually deleted from my draft list. This happened to me a few times.
I saved drafts, and then when it looked like iI could post, I would try to post all of them. Sometimes it worked…and sometimes it didn’t.
Just for giggles I clicked the “open draft” button once again snd this time it …opened my draft! Hurrah! I discarded it and now have the ability to create a new post. Thank you for whatever it is that you did!