How do I delete an old PC?

I just built a new PC for my daughter and I want to reuse the PC name but I am told it already exists, pick another.

I had some install issues and now have 3 different, unused, names for her new PC.

 

Now I am getting a message that I have used all 10 machines I am allowe.  How do I delete old, unused PC names?

 

Thanks!

 

Thanks.

 

So I have to click on a user (any user) and view what machines that user is protected on to remove a machine from being monitored.  That's just not intuitive to me, and I'm an 18 year IT vet.

 

Deleted the old PC's, so that's cool.

I just built a new PC for my daughter and I want to reuse the PC name but I am told it already exists, pick another.

I had some install issues and now have 3 different, unused, names for her new PC.

 

Now I am getting a message that I have used all 10 machines I am allowe.  How do I delete old, unused PC names?

 

Thanks!