Remove participant from an Adobe Distributed Form

Good morning

I am using Adobe Pro XI and have a distributed form that I sent to around 100 employees with email addresses within my company.  I have some people that have left since I began the distribution cycle, and would like to be able to delete their emails from the form.  When I go to tracker and email those who have not responded, I have to manually delete their email address every time I resubmit the form.

Any ideas?

Thank you for your help!