Removing unwanted virtual server (after migration) without disrupting DNS


I have successfully migrated a virtual server from Server A to Server B. What are the steps for removing the old virtual server instance from Server A, given that Server A still holds the DNS? I tried disabling the virtual server on Server A as a test, but this seemed to also disable the zone in DNS. Concerned that if I delete the Virtual Server I will also be deleting the DNS entry, despite it now pointing to the Server B instance, as I want it to remain.

None of the guides I’ve found cover this - they all seem stop and celebrate after the IP is changed and the TTL is changed back to default.

Any help much appreciated, as I am quite new to this.