eBay does remove negatives for a number of possible reasons; some good, some not so good, in my opinion. eBay does not explain why feedback was removed, so in many cases it is not possible to tell why it has happened.
There are plenty of sellers with bad feedback, so apparently it is not that easy to have all bad feedback removed.
eBay has no reason to shield actual cheating sellers from bad feedback; in fact, if buyers file claims for items not received or items not as described, if the seller loses and does not refund the buyer, eBay will have to make up the difference if eBay is unable to take the funds from the seller's account.
The feedback system is not perfect, but properly used it should still allow you to distinguish between sellers that have a history of delivering what they advertise, and those who do not. Even if a seller is able to have negatives removed, you can still see if the seller has received positive feedback for selling similar items or not. A lack of negatives does not mean anything if the seller also lacks positives.
If despite all that you still wish to close your account, see here:
https://www.ebay.com/help/account/changing-account-settings/closing-account?id=4199
