Router access help

My dad is I.T., however I have never been good with computers. He always challenges me and he challenged me with access to the router, I finally got it (default username and password) and when he found out he said, "Took you long enough"... Anyways, he changed the username and password and told me there is an easy way to do this. I have a netgear router. However, he said I can not reset the router. How do I do this


Thanks
-Briggs