Root Returning SGS4G to Stock for Warranty Return

[kmand]

How do I return an SGS4G to stock for warranty return?

 

[ko08]

Factory reset if on original rom

 

[Krogg]

Factory reset if on original rom

This might be a stupid question, but how is that done? Are you talking from the settings menu, or from recovery? I do not have a custom ROM, only updated from the settings menu, but would like to go back to 2.2. If it is needed I can load an .sbf, but can't find the right file to download. Anybody know where that can be downloaded?

Thanks