How to remove the MERIDA EXPERT TR / MERIDA EXPERT SL thru axle?

I got a new Merida Scutura Endurance 400 and I can't work out how to remove the front wheel.

The manual says 6mm Allen key or the key on the rear axle. The spec sheet says

axles MERIDA EXPERT TR / MERIDA EXPERT SL

including removable lever

6/4mm allen key

Anything less than 6mm just spins freely inside the axle and 6mm does not seems to fit at all. Not much luck removing the rear axle key. Did I miss some secret technique?