If you use the linkage editor to delete a control section that contains any unresolved external references, those references are NOT removed from the external symbol dictionary.
If the input does not have an INCLUDE statement or object module after a REPLACE statement that is to delete a CSECT, and there are external references to be resolved from SYSLIB, the linkage editor causes the delete request to operate on the first module from SYSLIB and deletes the control section.