NOTE: In 2018 Google renamed DoubleClick for Publishers (DFP). It is now known as Google Ad Manager.
For existing clients who are currently using the old DfP set up, this video explains how to switch to responsive ads with DfP.
Removing the Old DfP Configuration
NOTE: At the bottom of the page there is an option to "Remove my old DfP configuration." This option is available to clean up unused code once you have made the switch to the new DfP. Only do this once you are certain you've set up your ads properly on the new system. Once you remove the old configuration, there is no way to retrieve it again.