If you are doing web browser checkout - Click the red button (proceed to payment) so you can get to the prompt that allows you to opt out/remove SC Protect. Clicking "proceed to payment" does not mean that you need to encode your payment details as you will be led to the Review before paying section.
Below is what you should see right after you click "proceed to payment" (simulation below). On the right side that shows "Avail SC Protect" - move the button to the left so it will be removed.
This pop up message will appear asking you to confirm your decision. Click the "Checkout without SC Protect" hyperlink to proceed with SC Protect removal.
This is the next page that you'll see - SC Protect has been removed, total insurance fee is USD 0.00. 
If you are doing SC app checkout - The option to opt out/remove SC Protect can also be found on the Review before paying page (similar to screenshots provided above for our web browser checkout flow).