Yes!
To remove someone from a Split, go to 'Show Split History' on the release page, and then click 'Show Options' --> 'Remove' next to the email you want to delete.
Once they're removed, any earnings that were held will appear in your Bank within 24-48 hours.
(If you still want to split earnings with them, but they just need a nudge, then click 'resend invite' instead!)