Web apps monitors are not discovered in the traditional sense. SP201o has a shortcut that makes it easy to set up web url monitors on a list of web endpoints. This is just smoke and mirrors though - under the cover distinct web monitors are set
up. These are never "re-discovered" so if there is a web url monitor still alerting, trace back to the monitor it comes from and disable it.
You can't delete it without deleting everything in whatever xml file the definitions were saved in initially as an MP. If you want to start over, and if you isolated the webapp definitions to a unique file, you can delete that mp from the admin xml
list. But if you mixed things together in an mp like the default mp, you really can only disable the monitoring.
Microsoft Corporation
