There are several ways you can remove the Hello Bar from your website,

First one, which I highly recommend is setting the pop-up to "paused" this way you can always go back and unpause it in case you'd need to show the pop-up again on your website.

To do that, simply login to your Hello Bar account dashboard at then go to "Manage Tab", under "Manage", click on the "Gear" icon then select from the options.

 If you like to remove the pop-up completely then you can select "Remove" right below the "Pause" option.

Once you do either options, simply clear your browser's cache and the Hello Bar pop-up should no longer appear on your website when you view it again.