Very simple answer, depending on the product you registered:

If it is one of the modules:
In the configuration, set the "Display Options>>Show Graphic above module" to No

If it is one of the components:

MH2 Treasury (Configuration>>Extended Options)
MH2 Shoutbox (Configuration>>General Options)
MH2 Members Directory (Configuration>>General Options)

In the configuration, set the "Component Graphic Logo URL" image to blank