you accomplish this is a few steps. let's say you want to convert it to run as wasadmin <or what ever> (for the purpose of commands I'll use wasadmin).
If your tied to an ldap, Make sure you have wasadmin in ldap. If not, make sure you've added wasadmin to your linux users and add a group such as wasgrp)
stop all running processes for WAS. ./stopServer.sh <serverName> and if dmgr ./stopManager.sh
cd to the directory one down from where you installed WAS. (i.e. /opt/IBM/WebSphere) you'd go to /opt/IBM
there are two commands that run to give ownership and permissions for your directory.
chown -R wasadmin:wasgrp /WebSphere (this changes all WebSphere recursively to the wasadmin user and wasgrp ownership)
Then you have to make sure the permissions are done: chmod -R 755 /WebSphere (this makes everything run by owner and read properly) Depending on your version of linux you may need to use chmod with a 4th number) the important thing is that your permissions and file ownership should all now fall under your new wasadmin and wasgrp.
once that's done you must sudo to the wasadmin user to start the environments always from now on.
After updates/upgrades you'll always have to run the chown and chmod when done.
The environment should now run as non root. If you want to do the same for IHS it's the same process except for if your running security the ports are lower than what the env allows at 80/443 so the steps vary a little please let me know if your doing that too. Good luck and let me know if you need further assistance.
Regards,
Rene'