uploading - Should user be allowed to delete attachment that is required?

If attachments are required in a form that can be saved as a draft, should the user be able to delete it or replace only?

Answer

Let the user do what they want, then enforce your requirements at form submission.

Preventing deletion is no help to the user whatsoever. This does not help them successfully complete the form, but instead prevents them from fixing their mistakes. There's no need to prevent deletion when the user isn't even trying to submit the form yet.