Creating this post as I searched for this and did not get a direct answer.
What I found out:
If you used a tag for some posts but then deleted the tags from the posts, the tags will still be there in your tag collection.
If you want to delete them via the Ghost Admin Panel, currently you can only do it one by one on the tags page.
Also, some general perspectives on tags:
On many Ghost themes, only the first tag of a post is publically visible. According to Ghost documentation:
The first tag in the list is always given the most importance, and some themes will only display the primary tag (the first tag in the list) by default.
Therefore, post tags should always start from the most specific and progress to the most general.
Also, don’t invent a bazillion tags for every post to hack SEO, create tags only for categories with many posts. Why? Otherwise you will soon have a headache in your post management page.
It is also not useful for the readers. They expect clicking on tags to lead them somewhere, not nowhere.
Ghost.org docs tell you more about it.
#tags #tag_management
