Login Issues

Bit of a strange request but quite recently a good friend who was a wordpress designer passed away leaving a handful of clients without a goto guy. My company has taken on the mantle to try and help out his clients as he had a few on a maintenance scheme where by he would update theme, plugins back up etc each month for a nominal fee. The types of clients he worked with are smal non tech types whom relied heavily on him for everything. He created the sites and kept the login details. As you can imagine some want to move on but others are happy for us to carry on with the updates.

Is there a way that we can get to details? We have access to his mac but no login detail for his clients can be found. We have asked the clients and most say he had all that detail!! I presume that the admin pages for these sites will all be at mysite.com/wordpress/wp-admin??

Any help appreciated….