Why can't I delete this form?

I have a form that I am trying to delete. There is no red X for me to delete it, and when I select it, the Delete button is grayed out. 

I cannot for the life of me figure out why. 

• It is not the only form for the table - it is one of 7
• It is not used for any role for anything
• It is not used for any report override
• I've deleted all fields and all rules from it

I've even changed the name of the form to "ZZZZZZZZZZZZZZZZZZZZZZZ" to easily spot it in any role or report overrides. It isn't used, anywhere. I can't delete it. Why not? I'm tired of seeing it there.

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mtn mtn
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