Detected an installer lock file (/root/installer.lock). Please be sure that an installer is not already running. For a beginner, it is frustrating but the solution is clearly written on the screen, You can remove this file and re-run the cpanel install once you’re certain another installation isn’t in progress. You need to run a simple command from your shell to overcome this problem. You can remove the installer.lock file using this command:
rm -rf /root/installer.lock
Ok, you can easily install cPanel by command sh latest which will proceed the installation smoothly.