1) Login to cPanel and click on "Softaculous Apps Installer".
2) Click on "All Installations" button as shown below.
3) Locate the required installation and click on Backup icon.
4) Choose whether you would like to back up database or directory with files.
Also, you can add a note to your backup and will see some general info about your installation.
5. Click on Backup Installation to start generating the backup.