[hammyhavoc]

If you or they have access to the database, just assign you/them an admin role and/or change the password and/or create a new user.

Consider any contracts currently in place before you do something like this, and figure out who is the name on the hosting, or whose server it is.

[lazyasciiart]

The nonprofit appears to consider it a success and is embarking on a new project to buy/build/whatever a CRM that will do the things they originally believed the website project would achieve. I can't even get them to use Mailchimp reliably, and they want to solve that with magic technology.