To inactivate a Campaign you can Archive it.

1. Click on the "Campaign Icon" in the top, right of the page and then check the box to the left of the Campaign you want to Archive.

2. Click on the "File Box Icon" above the names of the Campaigns and the Campaign will be Archived.  

You can view all of your Archived Campaigns by going to the Campaign page and clicking on "Archived" in the box on the left of the screen.