I must leave the entire EU / Schengen area
You return decision will be registered as an alert in the Schengen Information System (SIS). It will remain in SIS until your departure from the EU / Schengen area has been registered. The authorities in all Schengen countries can see in SIS that a return decision has been issued for you.
If you do not leave Norway and/or the Schengen area before your deadline for departure, you may be deported and prohibited from entering Norway and/or the EU / Schengen area.