This will need to be done in the code.
If you're unfamiliar with coding I recommend looking for a Shopify Partner or Shopify Expert that can help you with this.
If you are familiar with code I can give you some direction. Which is that for the Debut theme, the padding at the top is on the "main" element with classname "main-content".
The padding at the bottom is actually a margin applied to a div with the classname "section-header".
Be aware that this "padding-top" and "margin-bottom" is reapplied at different screensizes.