To remove the factory radio:

Remove the rubber anti-slip mat which you’ll find in the tray on the top of the dashboard

Underneath the mat there are two Torx screws, these need to be removed

Once removed the top half of the dash will need to be pulled forward, use trim tools to release it and be sure to disconnect the hazard switch plug

Once removed, you will see two more screws, undo these to reveal the 4 screws holding the radio in place

(Please see addition images for reference)

NOTE: This guide is for a Golf Mk5, not all VW vehicles require the same method of radio removal