Either by abandoning it and choosing not to scrap the facilities, or by using an empty coloniser to plant it in the first place.
I've acquired a few zero pop planets from the Crysonlite in my current VS AI game. Easy money=-)
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"Pinky, are you pondering what I'm pondering?"
"I think so Brain but, if you replace the P with an O, my name would be Oinky, wouldn't it?"