Default Qi charger question

I glued magnets behind my dash in my car so that I can just stick the phone to it without having a clunky car mount. I have this charger http://www.amazon.com/gp/aw/d/B00HEN..._M3T1_ST1_dp_1 and the green circle behind the coil is too big to fit behind the dash. Can I remove that disc or is it necessary for the charger to work?

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