[SOLVED] How to return OEM license?

Apr 14, 2020
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last year i put on a retail windows 10 product key, now i've got new pc and i'm about to put the key to that new pc.
but however i want to deactivate the old pc's key and switch it back to OEM because i'm going to sell it.

are there any way to do so?

thank you.
 

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