You can delete APN search filters per data source.
To delete LDAP APN filters:
Click Search Filters tab.
Select it and click Delete.
The selected expression is removed from the list.
In the APN filters section of the window, select the expression in the list.
Click Delete.
Note: The filter is deleted without a conformation. However the deletion is not final until you click save. If you want to reverse the deletion, click Cancel on the Search Filters tab.