We do not provide tools to image the disk as a backup, nor does the ES have a factory reset tool built into it yet. Someday, perhaps, but not yet. Depending on what sort of things you're going to be playing with, backing up the /opt/mango directory is usually completely sufficient.
There are scripts for iDrive supplied with the ES that you can use for a remote site backup. https://help.infiniteautomation.com/setting-up-remote-backups/
If you're going to be playing with the USB utility, the udev rules, or something like that, you're best off creating backups of things as you go and exercising care along the way, asking questions when prudent.