Mobile view: how to remove right/left margin from the specific widgets?

You just need to add media queries for mobile screens.

Add CSS in the stylesheet.

if you want globally add this:

@media only screen and (max-width: 600px) {
  #pl-2040 #panel-2040-4-0-0, #pl-2040 #panel-2040-5-0-0 {
      margin: 0;
  }
}

If you want to implement only on the homepage try this:

@media only screen and (max-width: 600px) {
  .home  #pl-2040 #panel-2040-4-0-0, #pl-2040 #panel-2040-5-0-0 {
      margin: 1cm 1cm 1cm 1cm;
  }
}