How would you go about canceling out the effect of a radio wave by emitting another wave of same frequency, wavelength and amplitude
It is possible to cancel sound waves by detecting incoming sound waves and then generating another sound wave of the same frequency and direction but opposite phase. Because electrical signals can travel much faster than sound, the sound wave that cancels the incoming sound wave can be generated a bit downstream from a microphone, just in time for the incoming sound wave to be canceled. In other words, an electrical signal can be sent ahead of the sound wave to "instruct" a sound generator to produce the cancelling sound wave when the incoming wave arrives, and that makes cancellation possible.
However, it is not possible to send a signal "ahead" of an incoming radio wave, because nothing can travel faster than a radio wave (or any other electromagnetic wave), so active cancellation the way you envision can't be done.
There is a kind of complicated situation in which it is "sort of" possible: if the incoming radio wave is moving very slowly because of the medium it is passing through. Paraffin, for example, slows the speed of radio frequencies to about 2/3 the speed of light. If the incoming radio waves had to pass through a block of paraffin hundreds of meters thick, but were detected as they entered and an optical signal were sent ahead via a "tunnel" through the paraffin, the optical signal could in principle get to the far side of the paraffin before the radio waves arrive, in time to "instruct" a radio source to generate the right radio wave to cancel the incoming wave just as it arrives. I know that's not what you had in mind, but it's about as close to what you want as is physically possible.