If you are using the Enterprise edition of Advanced installer just go to the dialog editor(User Interface/Dialogs) select a dialog which contains the text branding, select it and change the text under Display.
I use the [Manufacturer] property myself..
I think you have to edit it on all pages containing the branding, can't really say for sure though. (maybe AI support knows a way to change all at once).
Remeber to turn off translation for the branding text too.
As Carl says it is something that at present you need to do on ALL the dialogs that will be used during your installers Installation but also during modification and repair as well, so you need to run through all sequences to ensure that you haven't missed any dialogs that you intend to modify.
It would be a relly nice feature addition to AI if this modification could be made once and once only.
In order to achieve this (as Carl and Dom already mentioned) you can simple remove or edit the related static text control from installation dialogs. Also, please keep in mind that our "Dialog Editor" feature is available only in an "Enterprise" or higher project type.