From the registration site, click on the top right corner “Already Registered”. Enter your confirmation number and email address. On the next screen, you'll see several tabs. Click on the “Modify” tab first then select "OK/Next." Click on “Registration” to the far right. You'll be taken to the current registration where you will select or remove applicable sessions in each time slot.
If you need to remove a session already selected in a certain time slot, scroll to the bottom of that time slot and click on “Unregister." Once you've made all your changes, these sessions will be removed when you click on the "OK" button at the bottom of the screen to proceed to the next page. Make sure you proceed through all screens. Your changes are not confirmed until you see the spinning circles on the screen confirming your changes.