The cancellation button will not show up for any pending invitations until they're two-weeks old. After the 2 week period, you should be able to cancel the invite. Here's how:
Click on the 'View Messages' link at the top of the page.
On the left, click the 'Invites Sent' link.
Click 'Cancel Invite' below the invitation you would like to cancel.
> The CafeMom Admin Team
at 8:41 PM on Jan. 9, 2009