Withdrawing doesn't break KYC (the record tying your identity to a Monero purchase - how much and when) it only helps with what you do with it after (forward privacy). Similar to withdrawing cash from an ATM, the bank knows who withdrew, how much, and when, but not what you did with the cash after.

The best thing you can do to "erase" your KYC record is sell it back to the same exchange (and rebuy your Monero elsewhere without KYC like Bisq or LocalMonero) so it looks like you have none left and maybe lost interest.