This requirement doesn’t sound right. Also what you have just experienced is a typical XY problem.
When naming servers the typical approach is first to name them and then install everything, not the other way around. In a typical environment these names are set by System Admins, not by individuals/server owners etc. A typical scenario will have a load balancer hence your connections will pass through a VIP and an F5 server. Which normally you shouldn’t have direct access unless System/F5 Admins and webMethods admins are the same people.
Changing instance name on the other hand, (which involves deleting the default instance, or not installing it at the beginning.) will usually cause more harm then good unless your server has multiple Integration Server Instances. It is usually not recommend changing the default instance, as others noted you will need to patch your environment manually if you change it.
I would ask for a confirmation for the requirement first. You may have misunderstood the requirement. Even if its true, you hardly ever need to do it at all. I would ask the reason behind it to understand the exact requirement. Sometimes client asks for something illogical. Its your job to tell them (nicely) that they are not making any sense.
Hope this helps.
#webMethods#Integration-Server-and-ESB#default-server-name