Need to Batch Remote Author

In cleaning up our authors profiles in old content, an arbitrary user has been default assigned to all posts. Beyond manually removing this profile from each post, how can we batch-remove the author? We have already changed the role to “none on this site” (the user was never an author and we do not know what resulted in their assignment as an author. The “author” appears as a number because it was a library account and this was their “display name”).

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