There are several reasons to factory reset your Core. For example, we recommend to factory reset the Core before reselling it, or as a last resort if you're experiencing issues and other troubleshooting steps don't work.
How to factory reset the Core
Simple navigate to "Settings" on your Core device. From there head to "Factory reset?", press the bottom button and select "Yes" by pressing the bottom button again. Your Core was now reset to its factory settings!