Removing Client-Level Pop-Up Alerts
From the Client Info page, scroll to Communications in the sub-menu, then select Pop-Up Alerts - List.
Click the check box next to the alert.
Other option: Don't delete the alert. Save it as part of the overall client communication record. Instead, when the alert pops up, select Do Not Remind Me Again and the alert will not appear again.
See the related article for creating client-level pop-up alerts.