When you use Visual Composer Elements inside rows, by default left and right padding will remain on both sides. But sometimes you may need to expand the row width to fill whole space and take all width. The following image is an example of what you may be after.
In order to expand this, you may need to go to Page Settings, and in the Row Settings > Edit > Row Stretch > Stretch Row and Content.
This will expand the row width and its content to the maximum available space. The following images shows the steps: