In Ubuntu I get error groups: cannot find name for group ID 1004 [closed]

I had a group called sknowed. It was group ID 1004. The user admin was a part of this group. I then deleted the group with sudo groupdel sknowed. When I execute groups command, I get a list of groups but one says 1004 instead of the name. 1004 was the original group ID. The group id 1004 is not present in /etc/group How can I deleted 1004 and the group?