Assuming you subscribe through Sky Sky Ultimate TV includes the Netflix Basic plan (1 screen + HD) You can upgrade to Netflix Standard (2 screens + HD) by adding the HD pack On Sky Q. You can upgrade to Netflix Premium (4 screens + UHD/HDR) by adding the Ultra HD pack (requires the HD pack first) on Sky Q.
Can you sign out of the Netflix on your Q box?
If you can sign in again with your own credentials.
If it is locked and you cannot sign out then you need to contact Netflix.