Select one or more CIs in the CIs in Service table, then click . The CI is removed from the CMDB database and displays. Your changes are immediately visible in the drop-down menus and displays.
There is no option to undo a deletion from the CMDB. To restore a deletion you must find the CI again and re-associate it with the Service.
And when you delete all CIs from the list, the Service is also removed from the CMDB. A given Service can only exist if it contains one or more CIs. If the Service no longer exists as a result of removing the last of its CIs, you must also recreate the Service (by typing the names of the Owner, Area, Group, and Service).