Hi jamzee500,
Thank you. We appreciate that follow-up information.
A few other points to consider; have you ever contacted this person using a third-party app like WhatsApp, or Messenger? If so, you may want to see if this person is part of the contacts in those apps. Also, do you sync contacts from any third-party services? You can check by tapping Settings > Accounts & Passwords.
If everything above checks out, you might try this test. This will help determine where Spotlight is finding that contact. Tap Settings > Siri & Search. Then, under the "Siri Suggestions" section, make sure that Suggestions In Search is off. Then, with it off, try searching and see if it still comes up with that contact.
If it doesn't, then switch "Siri Suggestions" back on. From there, go back to Settings > Siri & Search, and then you can adjust the settings for specific apps by tapping one in the list. In this case, try starting with tapping Phone and Contacts, and then disabling "Siri & Suggestions" on that next screen. Once disabled, try searching to see if it still comes up. This is meant to help determine what source that contact is coming from, and that information may help get to the bottom of this.
Take care.