What happens if I am removed from a client's site and I have WPMU Dashboard installed?

I understand that the only person that will see the WPMU Dev Dashboard is me (the person that uploaded the plugin and activated it). I see the value of having this plugin installed on my client’s sites. My question is what happens if/when that client stops using my services? If they give me notice, I can go in and remove the plugin from the site, but if they decide to remove my access before I can do that, they will then have access to my wordpress account, and with that access to the WPMU Dev toolbar.

So is there a way to remove the wpmudev toolbar from a site that I don’t have access to anymore?