How do I remove the WPMU Dashboard?

I am passing a site onto a company who will cease to be my client.
I don't want to remove the wpmu plugins.
I understood that use of the plugins was allowed, even if wpmu membership ceased.

1 I don't want to remove the nag screen, I want to removed the wpmu dashboard plugin completely for security.

2 I want the company to be able to use the plugins.

I've read the posts about removing the nag screen, which I understand. But this option can easily be reset, the dashboard plugin be installed and all my payment & password details will be available.

At the moment the only solution I can see is to cancel my membership and to rejoin as a brand new account, thus breaking the link.

Is there another way?

I am encouraging the company to join wmpu, but at the moment they can simply continue to use my membership via the site.

Can you assist me?

David