As long as your distribution has not yet been sent out, it can still be edited or rescheduled.
Step 1. Go to your list of distributions by clicking on "Manage" on the Agility toolbar then select "Email Distributions".
Step 2. Locate the distribution you would like to edit or reschedule. Under the column "Actions" click on "Edit" to either edit the content of your release or change its release schedule.
Step 3. Confirm that you wish to proceed with editing your scheduled release. This will re-set the release to a draft state.
You will then be taken back to stage 1 of the distribution process where you can make any and all the changes you need.