There is no single "Reset Family Settings" button on the Xbox 360 dashboard. To effectively reset, you must delete the existing family profiles and create new ones, or perform a full factory reset as a last resort.
Notes: You need the console passcode. The Xbox 360 is no longer supported by Microsoft; some online features are unavailable. If issues persist, consult archived Microsoft support pages or community forums like Reddit's r/360hacks for legacy guidance.