It is always a good idea to secure a backup for your website files. If anything unexpected happens, you can always revert or restore everything back to normal.
Here’s how to do a full backup in cPanel:
Login to cPanel
Click Backups
Click ‘Download or Generate Full Website Backup’
In the next page, you can see lots of options. Backup Destination is the location on your server where the backup would be stored. Home Directory is okay. The displayed Email Address would be used to notify you once the backup is complete. Just accept the default settings and click Generate Backup.
Check your email for a notification informing you of the status of your backup.
Alternatively, you can check your root directory and look for a compressed backup (filename would be something like this : backup-2.10.2009_00-26-56_cpanelusername.tar.gz)
Once verified, check the box right next to it and click Download to save it on your computer. (Assuming you are in the File Manager window)