Warnings
This is not a toy to just play with. (Unless you use crouton) If you have WP (Write-protect) disabled, be careful with what you are downloading. Read every part, explore the web and see other people’s experiences with this. Always check that it can be done with your model, otherwise you might brick your device unless you are prepared to have another option.
If you have modified the BIOS and want to reset them, follow the instructions in the links. You can also email MrChromebox at mrchromebox@gmail.com. The website covers how to restore your chromebook to factory settings if you had installed Windows 7/10 or Ubuntu and you want to use another method or you want to use your chromebook as it is. For this recovery option, there are specific things you need to buy. You can also use the Chromebook recovery utility, but you will need a MicroSD card or USB with more than 8GB storage.
You have been warned.