Web Application WAR file -> File Refs tabbed pane
In the File Ref's tabbed pane, you can edit the list of , JSP , and error mappings.
To delete a file from the list, select the row containing the file and click Delete File. A confirmation dialog will ask you if you really want to delete the file from the list.
In the JSP Tag Libraries section, list the tag libraries and their (TLD) referenced by this WAR file.
To delete a tag library from the list, select the tag library and click the Delete Tag Library button. A confirmation dialog will ask you if you really want to delete the tag library from the list.
In the Error Mapping section of the File Ref's tabbed pane, you can indicate the URL that must be accessed when a particular error occurs. For example, you could enter `404' in the Error/exception column and '404.html' in the URL column to indicate that the 404.html file should be opened when the 404 error occurs.
To delete a mapping from the list, select the row containing the mapping and click
the Delete Error button. A confirmation dialog will ask you if you really want to delete the mapping from the list.