Hello! I'm Jen, and I'd be happy to help you out with this issue.
To remove someone's sign-in information from your PC, please follow these steps: Click Start > Settings > Accounts > Other users > Select the person's name or email address > Select Remove. You may also visit the following article for more information. Thank you.
https://support.microsoft.com/en-us/windows/add...
I hope this information helps. If you have any questions, please let me know and I'll be glad to assist you further.
Best Regards!
Jen :)