How to Exclude Not in... Results from Mixpanel Cohorts

Hi community, I'm pretty new to mixpanel and I have an issue with the results I get on my metrics charts: I'm creating different cohorts using clients emails to separate them by company. When I get the results I keep getting the "Not in..." results I'm not interested in. Is there a way to get rid of these results permanently? Am I doing something wrong? thank you for your help in advance!