The source removal step will keep or remove the gateway from DPOD.

Choose "Remove Source Gateway" - to remove the source gateway from DPOD.
Even after the gateway is removed from DPOD, you will still be able to see old transactions and syslog data from this gateway in DPOD (depends on your storage capacity)

Choose "Keep Source Gateway" to keep the source gateway in DPOD after the migration is done.
The Secure-Restore process will assign the same source IP address to the target gateway - so if you wish to keep both - you will need to manually change the source's IP address and enter it in the input fields  "New Source Gateway SOMA Address","New Source Gateway SOMA Port","New Source Gateway ROMA Port" and "New Source Gateway Log Target Source Address".

Next: Pre-restore validations