You can find out which files are linked via this command

DSPDBR FILE(LIBRARY/FILE_NAME)

And in spool file you can find results

Files Dependent On Specified File                                     
  Dependent File         Library       Dependency   JREF    Constraint
      FILE_1             LIBRARY1      Data            1              
      FILE_2             LIBRARY2      Data            1              

Then you can try first to delete member with same name in joined logical files

You will need information about Volume serial and Sequence from BRMS

Code 4 -- Journal sequence number is at the maximum value.

Means that Sequence number is on maximum level (this is screenshot from MIMIX) :

Best way to generate key pair is to use ssh-keygen utility: 
ssh-keygen -t rsa -b 4096 
ssh-keygen -t dsa 
ssh-keygen -t ecdsa -b 521 
ssh-keygen -t ed25519