The PowerStore relies on users being logged in to record the transactions properly for that user. This is an integral part of how PowerStore works and altering this functionality could potentially cause your store to not work properly.
You would have to remove the validations that are on the checkout page for the logged in user as well as the ones that are on the confirm pages. This would make it so the user is not forced to login, you could remove the login forms or add some messaging to them after this.
