Many ID cards have holograms embossed on them to make them harder to duplicate. You may want to remove the hologram for several reasons. For official IDs, it invalidates the ID, making it a good way to save old IDs while ensuring that no one else can use them. For unofficial IDs, you may want to simply make it less flashy. Whatever your reasoning for doing so may be, removing the hologram from ID can be done quickly and at home.
Put the ID in an airtight plastic bag. Seal the bag.
Place the bag so the card is facedown in a pot of boiling water.
Remove after two to three minutes. This will have melted the adhesive holding the hologram on. While leaving it in until the hologram falls off entirely will work, boiling the ID for that long will likely fade the ink elsewhere.
Gently rub the hologram with a soft cloth. It should come off. If parts of it remain stuck, boil it for another minute then try again.
This process leaves the ID near intact (if left in the water too long it might fade, as noted above), but destroys the hologram itself. Holograms are made to be impossible to remove intact.