On the source side you would do the following:
DELETE TRANDATA HRSCHEMA.EMP
DELETE EXTRACT MSEXT
DELETE RMTTRAIL /u01/app/oracle/gg/dirdat/ms
Note that this command only deletes references to the specified trail from the checkpoint file. It does not delete the trail files themselves. To delete the trail files, use standard operating system commands for removing files.
On the target side you would do these corresponding commands:
DROP CHECKPOINTTABLE gg_user.chkpt
DELETE REPLICAT MSREP
Deleting the Extract and Replicat will remove the checkpoint files but leave the parameter files intact, so you can then recreate the groups as desired.
Let me know if you have any other questions.