can not delete a user account on my MacBook pro

A user account appeared on my login screen: with sign in fields of a user name and password, listed as other, now i have my account, a guest account and the account that appeared listed as other. When I try to go into Users & Groups to delete the account, it's not there to delete, it only shows my account and the guest account. How do I delete a user account that does not appear in the User's & Groups? Running Mojave 10.14.6