In House of Cards, Frank was discussing something with his underling in his office, when someone told him, "Sir, (State) Secretary is here".
Frank said, " Thank you. Send her in", and then told his underling," Excuse me".
After that, his underling left.
I think "excuse me" is a polite way to say" you can excuse yourself now" or "you can leave now" for such a situation, right?