The reception centre where you are staying can help you to apply, and they or the UDI will decide whether or not you will be granted leave of absence.
You use this application form (in norwegian only): Application for leave of absence from a reception centre (pdf, 130 kB).
You are not entitled to leave of absence.
Your application will be considered based on whether you
If you are staying at a reception centre for unaccompanied minor asylum seekers, there must be adult caregivers in the place you are going to stay while you are away from the reception centre.
There is also a limit on for how many days and how many times you can be granted leave of absence.