How do I turn the radio in a pi 3b off

[Gene Heskett <gheskett@shentel.net>]

Greetings all;

How do I turn the radio off, completely off, in a pi 3b? I have no use 
for it to be on, inviting a "drive by" attack or wasting cpu cycles.

An iw wlan0 scan finds as many as a dozen signals, one quite a bit 
stronger than the others call's its SSID: "Fbi surveillance van." I even 
catch the next door neighbors hp printer.

Thank you all.

Cheers, Gene Heskett
-- 
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