To turn off the ability for volunteers to submit request forms via Web Terminal after the schedule has been created, you should go to the Web Terminal pane on the left hand side of MSP's main screen.
1. Click on the "Web Terminal settings..." button.
2. Click on the My Profile tab.
3. Uncheck the "Allow volunteers to submit request forms to change their profile at this time" checkbox.
When your volunteers log in to their profile they will see a message that they can not currently submit change requests.