An alert destination cannot be deleted when it is being used by an active test. The grayed out Delete icon ensures that an alert destination that is in use is not accidentally deleted.
If you no longer need an alert destination, any tests using this alert destination need to change their alert destination to go to the alerts log only. To do this:
In the Gomez Portal, click the Admin tab.
Click the Alerts button
Click the Edit Alert Settings icon for the test whose alert destination you want to change.
In the Notifications sections, select no destination (alerts log only) from the Destination/Subject line drop-down list.
Click Submit. The test no longer uses the alert destination.
Once the alert destination has been removed from all tests, the Delete icon in the Alert Destination page will be active and you can delete the alert destination.