Content > Link Lists > "Alert Bar"

This will auto-rotate through alert text in the header area, and each alert should be setup as a separate item in the link list. Within each item, only the name and link fields are used. 

To turn off the alert, simply make sure there is no content in the section OR you can re-name the link list (eg. "Alert Bar - Off") and then you can label the section back to "Alert Bar" when you would like to turn it on.