reinstalling OS on a used mac
I have been given a used Macbook with High Sierra OS and the original user’s details. He has given me his username and password but not his iTunes log in details and I can no longer contact him. Will this prevent me from reinstalling the OS in my own name and, if so, will I be able to use my iTune log in details? I recognise that there are numerous posts on this subject on the internet but many are old, outdated or contradictory.