I don’t believe there is a way to turn off active mimoCalls that are in a document. However, you could turn off your internet or use an app such as Little Snitch to temporarily disable mimoLive’s internet access.
Something else you could do that I’ve been doing for many different reasons is create your own call-in links. You could easily disable or change the redirect link while you’re actively working on your project (though I am personally not really worried about people logging on while I’m working on stuff). I’ve detailed the benefits and my workflow in a separate forum post: