How can I delete this attribute from the collection.

I'd like to remove this attribute from a collection but it's been stuck for days with an alert saying that it wasn't even created in the first place. My question are:

1. Why is it there if it wasn't created successfully?
2. Why is does it show successfully deleted yet it doesn't go away from the attributes of this collection in the database after deletion?
3. If I need to create an attribute with the same name in the same collection, how can I achieve this?

Thanks any help is welcome.