Explanation
One way of preventing an existing payment page from being shown on the checkout payment page is to remove the payment type associated with the payment page from CO.pmts, then rebuild and activate a new cache. This will exclude the payment type from the list of available payment options on the checkout page.
The other options are either not feasible or not effective in hiding the payment page. Salesforce References: B2B Commerce and D2C Commerce Developer Guide, Payment Configuration Settings