You need VAGCOM software to do so.
Resetting an 2008 Audi A3 TDI service light can be done two ways. One by addressing the problem and the other way is to unhook the battery cables for up to a minute.
Indicator lights on an Audi can be reset by a mechanic. The cars manual will also give instructions on how to reset this light as well.
I Think its a main dealer job only as they use a guided function with the Audi VAS computer to reset the service display
with a dignostic tool
The service indicator on an Audi A6 can only be reset with something called the VAGCOM. One may be found on line but it would be better to take in into an Audi dealership or authorized mechanic because more damage can be caused.
You will need to take the 2006 Audi A6 to a mechanic to have the service light properly reset. In some cases, a person can undo the battery to reset the light.
Click the link.
A combination of pulling and pushing the 2 speedo buttons at the same time. This should reset the service light.
use a service rest tool or go to menu find service reset (be stationary lol)
A combination of pulling and pushing the 2 speedo buttons at the same time
Switch off the ignition and press-hold the service button (near the rev counter) and ensure the "service" message appears and wait for a second. Press the reset button again and that will bring the "service" message again or show the service due time remaining. The readings will reset after 5 or more seconds.
2009 models can be reset using the centre display panel going to "car-settings" and just scrolling down, it will not alter the long life service, for that you need a scanning tool.