Deleting the SCH C doesn't affect the version being used. The only way to get to a lower version of the online software is to clear your return and start over from scratch. If you have already registered or paid your online fees, then this option is not available.
TO clear your return and start over you must first have the return open so you can edit it. Then select Tools on the left, followed by the clear and start over option. Note that you will lose all data already entered when you do this, and will have to start all over.