Incorrectly tagged a face in photos and cannot undo?

Hi everyone,

I'm loving the new face detection feature on photos, but I have found that there apparently isn't any way to undo incorrect tags. It is very frustrating because my father and I share the same name, and I accidentally hit my own name suggestion after typing our name in and now a lot of his pictures are mixed in with a bigger bunch of mine. I wish there was a way to undo this or to manually tag a face in the photo (right now in photos, mistagged pictures with my father, my brother, and myself only show my brother and I under "people"). If anyone has a potential fix to this let me know, any help is appreciated! Thanks!