Hi,
step-1 remove the affected server from rz12,sm61 and smlg. This will make sure that no new job starts on this server while you are preparing to shutdown the app server.
Step-2- You need to make sure that all business critical jobs should finish if they are running on affected server. If only house keeping jobs are running and if those can be ignored then you can restart the server.
Step-3- Restart the server.
Step-4 Revert the changes done in rz12,sm61 and smlg.
Regards
Krishan