The Clear Restrictions Passcode command is used to remove a passcode that has been set to prevent restrictions from being changed. A restrictions passcode must be set on device for this command to show in the admin.
You can make an Apple Profile that would prevent a restriction passcode from being set.
You would use this command to remove the passcode if one was set that you don't know (or was forgotten). Note that you must have the proper management of a device to issue this command (for instance it could not be sent to a User Enrolled BYOD device).
Use the ellipsis (...) to the right of the device in the View - Devices and select "Clear Restrictions Passcode"