There is
no same-day deadline — you can change or cancel right up until the session starts. What it costs depends on how close you are:
To move it: tap
Change Session and pick another time that same day. The credit moves with the session, and no fee applies. The new time has to be more than 2 hours away.
To drop it: tap
Cancel. More than
2 hours before the session it’s free and the credit comes straight back. Inside 2 hours it’s a late cancellation, and you choose:
keep the credit and a
$20 late-cancellation fee applies, or
give the credit up and pay nothing. On an unlimited membership there’s no credit to keep, so a late cancellation is simply the
$20 fee. Once the session has started it can’t be canceled.
Full walkthrough:
How to Cancel a Session.