To activate or pause a campaign, select the campaign and click on the play or pause icons in the top of the My Campaigns view. When you pause or activate a campaign all the ad sets and ads belonging to the campaign will be paused/activated as well.
You can archive campaigns, copy campaigns and update the name and budget, by clicking on 'Actions' at the top of the 'My campaigns' view.
When you delete folders or campaigns, make sure to check that you are deleting the correct content. When you click delete you will be prompted with a warning window describing which folder or campaign you are trying to delete.
Please note: If you have set up Scheduling, Rules or Ad Rotation for your campaigns, you first need to disable the automation before you can manually pause or play the campaign.