Sallymelek There's several ways of addressing this issue. One of them (and probably the best solution) is highlighted here
Essentially, you'd be looking to leverage app.session.user which will determine if the user is logged in or not. If they are logged in, then the banner isn't displayed.
Another option would be to use something like Bootstrap's alert code
<div class="alert alert-warning alert-dismissible fade show" role="alert">
<strong>Holy guacamole!</strong> You should check in on some of those fields below.
<button type="button" class="close" data-dismiss="alert" aria-label="Close">
<span aria-hidden="true">×</span>
</button>
</div>
A "cheaper" (and arguably much simpler) method would be to place the announcement in the Welcome Hero itself
"
This would allow the end user to decide if they want the Welcome Hero displayed or not. If they click the "x", then this effectively dismisses the Hero altogether.