Hi Valerie,
I had to actually look up this one, because I thought it was already possible. Turns out I have forgotten completely to implement an exclusion field along with the actual exclusion code.
Because it’s not implemented yet, the only solution is to use a custom code for that. Use this code in the functions.php file in your active theme directory (copy from line 3):
You will have to change the $user_ids array to the user IDS you want to exclude. You can add as many as you want. I hope this helps!
I will make sure to add the missing option for the upcoming release.