Quick HOWTO: Reset Jenkins Admin Password

To reset the jenkins admin password, You can simply disable the security in the config.xml file.

1. If your jenkins is running on the Linux OS, edit the below file.

vi /var/lib/jenkins/config.xml file.

2. Search for the word <useSecurity>true</useSecurity>
and change the word true to false

3. Restart the Jenkins server.
service jenkins restart

4. Now go to Jenkins portal and set the password again.

5. Enable the security again by changing settings to <useSecurity>true</useSecurity> and restart the Jenkins again.

Note: 

If your jenkins is running on Windows OS, config.xml file located in C:\Program Files (x86)\Jenkis\ folder.