There is no de-kyc-ing. Once the government knows how many sats you have, they know how many sats you have. That knowledge cannot be erased. If you sell to exchanges, that is what the tax man considers "realizing your gains" and be prepared to get tax if they ever look into it / if you ever get audited. It's good for you to keep in mind that going forward, you might want to stack in a non-kyc kind of way (which you seem to be already doing anyways).

If you want privacy of your sats obtained from kyc exchanges going forward, you can use coinjoin or pass the sats through lightning like what Darth said. That can help break the link between these sats and your identity going forward, which allows you to spend your sats in the future with more privacy. But what's in the past is already set and cannot be erased.