To dismiss a case, click the Dismiss case button in the upper right. You can also use the checkboxes to select multiple cases and use the Dimiss button that appears at the top of the case queue to dimiss them all at once.
To mark a case resolved, click the Resolve button in the lower right.
Dismissing a case means that there was no action required, there was nothing of concern, or the flagged activity was a false positive. Resolving a case means that outreach was made or the case was resolved.