Mesh in front of the driver helps to tone down the 10kHz peak. It protects the driver too from dust, earwax, boogers, snot, etc. Don't remove unless you have another similar piece of material to replace it or experiment with. DO NOT remove the mesh behind the driver unless you are an advanced modder. Removing the stock mesh behind the driver almost always results in frequency response aberrations from the midrange to the treble. The best T50RP mod I have heard (and measured) leaves that mesh alone.
What are your goals with the mod? What are the stock T50RP's sonic deficiencies which are trying to correct?