You may withdraw your registration while it is pending approval and/or if the organizer permits it.
Log in to Indico. Go to the page of the event you have registered for. In the blue Application status bar, click See details.
A summary of your registration opens.
If the registration is pending, click Withdraw.
If the registration is approved, click Withdraw.
If the registration is rejected, you may no longer withdraw it.
A message appears on-screen. Confirm the withdrawal by clicking OK.
There is no Withdraw button!
Contact the organizer. It has not permitted modifications.