You should note that the ip of the super admin will be hidden from everyone in posts and at the online list, including to the super admin himself/herself as well.
Installation. First unzip the mod package and ftp the library folder inside to the root of your forum folder. Then go to your Acp->Add-ons->Install New Add-on->Install from uploaded file: Click the Browse button, locate the addon_HideIpSadmin.xml file inside the mod package and ht the Install Add On button.
To configure the mod go to Options in your Acp->Messages and all the way to the bottom you will see 2 new options. One is to enable/disable the mod and the other to enter the id of the super admin. By default it affects those Super Admins whose user id is 1. If your user id is not 1 then enter your custom uid at the second setting.