Hi there, each section inside the platform is given its own padding/margins to make it as easy as possible for clients to make a site without having to code in all the additional styles. If you're looking to remove that styling for something custom then currently the only way is to use css unfortunately. Platform is one of our older themes, so this is something we're looking to improve on in newer versions of the Pagelines Framework, but adding lots of additional options inside of each of the section panels tend to confuse people, so they've tried to keep everything as user friendly as possible.
If you've hired a developer to assist then they'll be able to track down the css selectors using that method above, using a web developer tools to look up and adjust the css elements on a site will probably be something they do daily, so they'll be able to correct that quickly for you.
Unfortunately we're unable to assist directly with css customizations as it's classed as site design, but we can always point you to the correct resources when you get stuck to learn the correct way to make the adjustments or offer assistance if we notice something obvious or incorrect in the code you've found to make the adjustments.