To remove the Payment tab/Payment Gateway:
  1. Navigate to Enrollment management > Admissions > Admissions setup.
  2. Click Application forms.
  3. Click the Edit Form button to the right of your Application Form.
  4. Select your Payment tab.
  5. To the far right of Payment, click Block Settings.
  6. From the Payment Gateway drop down, select "-Select an Option-."
  7. Click Save.

This will remove the Payment tab from the view of applicant families, but it will always remain in edit mode and preview mode of the Application Form.