Login to the Jenkins and navigate to the Manage Jenkins -> Manage Users. Now you will be able to see the current users on the Jenkins.
You should be able to land on the URL similar to this:
On the Left hand side menu Click on
Create User and follow the process. .
With this process you will be able to create a new user using the Jenkins’s own user database.
You can also ensure the Jenkins system user details from the jenkins server by navigating to the path $JENKINS_HOME and from the file
[root@node02 jenkins]# grep -w builduser * users/users.xml 2>/dev/null users/users.xml: <string>builduser</string>