Radiation isn't a problem - that's FUD (Fear, Uncertainty, and Delusion). Think misinformation. Your case will block most of it, that's kind of why the antennas are outside it in the first place.
The antennas are needed to get any meaningful reception whatsoever, as they are tuned for the frequency of the signal. It might work if directly on top of the base station, but with very low signal strength
Just unscrew the mini-PCIe board from the motherboard (small, maybe inch square PCB with two leads attached to it), and pull it out. Unscrew the connectors from the I/O panel.