I had this problem. Hopefully this will be useful for other people if you’ve already solved it. All names used to name faces appear in the Keyword List down the right side of the library, keywords used for name recognition have a property option ticked called people. Any tag with that property may appear as a suggested person. Simply delete the keyword or edit the keyword and untick the people option. After a while, depending on how many photos you have, Lightroom will update it’s suggestions.

No, not that I know of. You can delete the face regions from the incorrectly marked people to remove those faces from that name though. See part 2 of this article: https://lightroomkillertips.com/finding-people-in-lightroom-classic-part-2/