Straight from the products support page.
To disable Deep Freeze:
Hold down the shift key and double-click the Deep Freeze icon. Alternatively, you can press CTRL+ALT+SHIFT+F6.
Enter your password and click OK.
If you have not yet entered a password you should be able to click OK without entering a password.
The Boot Options dialog is displayed. Select "Boot Thawed" and click OK. This will disable Deep Freeze on the next reboot.
Reboot your computer. After the computer reboots, you are ready to uninstall Deep Freeze.