You need the Global Messaging Adminpermissionto delete aglobal message. You would delete a broadcast message after it has been sent if you neglected to select an end date for the message and you want to remove it from user Dashboards. You can also delete a global message before it has been sent if circumstances change and the message is no longer valid or relevant.
Click the Gear Icon in theNavigation Toolbar, and click the Global Messaging link in the menu.
In the Global Messages screen,locate the messageyou want to delete under the Alert, Information, or Warning heading.Global messages are listed alphabetically by the subject of the message.
Click the global message record to display a screen whose name reflects the subject of the message, and clickDeletein the toolbar.