There are no ways to reset a tuning setup to the default values while in a practice session in the Builder’s Cup.
In the event a player makes numerous adjustments to the tune and still isn’t happy with it, they have no way to reset to the default values and start over while in the practice session.
Another feature that would be really cool that I’ve been waiting for years for is to be able to reset individual tuning values to default settings rather than the entire tune.