Is there a way to change the account name we’ve set up?
Yes, you can, click on the menu and then move to administration, select the account and then change the name, by clicking on rename.
Hope this solves it for you
If the question was more about the domain name (yourname.piwik.pro), then it’s not possible. You have to create a new account then. Enterprise plans give you an option to assign a custom domain which gives you full flexibility in that matter.