Cannot delete Sophos Endpoint as Administrator

I am using a MacBook Pro. I had Sophos Endpoint as free anti-virus software. I have deleted Sophos from Applications and emptied the trash. No Sophos applications appear to be left on my MacBook. However, Sophos Endpoint still appears as an administrator when I boot up the computer to log in. If I go into "Users and Groups" in System Preferences, Sophos Endpoint does not appear, so I cannot delete it in the usual way that one would delete an administrator. What can I do to delete it? Thank you for your assistance.