The Delux De-Modificator is a upgrade terminal used for removing mods from weapons. It is completely identical to the Augmentrex 3000 by design, for this reason they are placed separately from one another, to prevent players using the one instead of the other by accident.
When operating the Delux De-Modificator, place the weapon You wish to remove the mods from in the top window, and then press the "Remove mods" button at the bottom of the interaction screen. The removed mods will appear in the bottom window.
There is a fee a player has to pay when using the Delux De-Modificator, and it is based on the quality, level and amount of the Mods, and the quality of the weapon. This fee is however very low so don't be afraid to experiment and swap out mods.
Do note, however, that individual mods cannot be removed from weapons. The Delux De-Modificator removes all mods from the selected weapon.