Boramkiv is right, the only way to clean the inside is to open the headlights, but they are VERY difficult to close up again afterward. You will most likely end up with moisture inside the headlights and short circuits later on as the moisture corrodes things.
2014 535i - MSport, HUD, NAV, Prem, Surround View, Driver Assist
2008 550i (R.I.P.)
2005 530i - Prem, Sport, NAV
2006 Jeep SRT-8
2003 Infiniti G35 coupe