If the printer's manual says it's 9 milimeters, that's as close to the bottom as you're going to get. The printer's margin is a physical limitation on how close to the edges of the page the printer can print. This limitation exists in almost all laser and ink-jet printers.

>I am using to print HP Deskjet 692C with A4 sheet. The manual of this
>printer says that the bottom margin is around 9 milimeters. I would
>like to print with 3 milimeters of bottom margin.
>
>I am using VFP 50a. Is there a way to do this?