The content for your Alert Bar is edited in the Link List (CONTENT > Link Lists) Alert Bar.

The "Name" field controls the text use for the link within the alert.

The "Link" field controls the what the "Name" text is linked to.

The "Description" field controls what is between the icon & the link.

The "Icon Class" field controls the icon that shows up on the left of the alert. Available icons can be seen HERE

To turn your Alert Bar "on", simply keep the name of the Link List as-is - so leave it as Alert Bar.

To turn your popup "off", simply change the name of the Link List - we suggest something like Alert Bar Off. 

In order to turn it back "on", change the name back to Alert Bar whenever you'd like. 

The code for your page searches for a Link List Alert Bar, and if found, displays the content inside. Changing the name of the section "breaks the code" and therefore removes your popup from appearing.