A family of Microsoft word processing software products for creating web, email, and print documents.
The entire background of the template is a single full page size graphic, so it is not possible to remove parts of it using Word. You would need to edit it in a graphics editor. The margins shown on the template are a function of the graphic size vis-a-vis the size of the page. To change the outer margins you would need to change the size of the graphic. The inner margins cannot be changed without editing the graphic.
The template background is not intended to be changed. You can edit the textual elements only.
The multicoloured fill in the first column is a separate graphic and can be both selected and deleted to leave the underlying colour of the background.