You have 3 ways to reset your Node/Pro:
1) A soft reset that will remove all your data. Go to the settings menu > 'About' > 'Node/Pro reset' > 'Reset settings & clear data'. All your data will be wiped. This is a good option if you're planning to give/transfer your Node/Pro to someone else and you don't want any logged data to be on the device. When you restart the Node/Pro, you will be prompted with the original initialization wizard.
2) A soft reset that will remove your settings but keep your measurement data. Go to 'Settings' > 'About' > 'Node/Pro reset' > 'Reset to factory settings'. All your settings will be wiped, but your historical measurement data will be kept.
3) A hard reboot that will get you back to the factory settings of the device (your historical data will not be affected!). Take a pin and insert it in the hole that is in the red square. You should hear a click.