How to eliminate mobile phone reception

Legally you can't.

If your disabling cause an emergency call to not go through you would be liable for damages, if you were to disrupt communication in most countries you would be in violation of many laws regulating broadcasting.

I understand it may be a trade-off if the sistuation is about something like blasting areas, etc. But the devices that would hamper communication would be just as bad as phones themselves, if not significantly worse due to the power required to disable/override others' phones.