If the system doesn't recognize the merge field of the address in the campaign, it will add it at the bottom automatically.
To avoid this, you need to add [CLIENTS.ADDRESS] where you want the address to appear in your campaign. It will pull the company address you entered in the Company profile page. You will then be able to edit the [CLIENTS.ADDRESS] field with the font, color and police.
You will be able to see the result at the next page, when you can schedule the campaign.