Please note: this article is only valid for Untangles running kernel 3.16. (How can I tell which kernel I'm using?)
1. Reboot the Untangle. To get into the Grub menu, start pressing the up arrow rapidly after reboot so that the menu doesn't disappear after 3 seconds.
Note: This procedure may not work over KVM as some keyboards may not be detected while editing GRUB.
2. Edit the GRUB boot options by selecting the version you want to use and press 'e' on the keyboard.
3. You will then see this screen. Using your arrow keys, move your curser to the end of the line highlighted in yellow and type init=/bin/sh
4. It will then look like this. (Notice the part in green has been added.)
5. Press CTRL-X or F10 to reboot. You will then get this screen:
Enter mount -o remount,rw / then press Enter.
6. Then enter rm -f /usr/share/untangle/settings/untangle-vm/admin.js and press Enter.
7. Type exit to reboot
8. You will then boot normally. Your username will be admin and the password will be passwd.