Here is what ebay has to say about Mutual Feedback Removal
Mutual Feedback Withdrawal allows members to withdraw Feedback they have left for each other, if both members agree to do so.
When Feedback is withdrawn, the positive, negative, or neutral rating associated with that Feedback comment will no longer show or count in your Feedback score. However, the Feedback comment itself will remain.
The Mutual Feedback Withdrawal Process
If both members agree to mutually withdraw the Feedback they have left, they both need to complete the Mutual Feedback Withdrawal form. Both parties will then have their Feedback scores adjusted at the same time. Depending on the type of Feedback withdrawn, each party's score could increase, decrease or remain the same. eBay will add a note to the Feedback comment, saying that the Feedback was mutually withdrawn.
After withdrawal, no additional Feedback will be allowed for this item.
You should only make requests for Mutual Feedback Withdrawal if both you and the other person have already agreed to have the Feedback removed in advance. There is also a limit of five requests per 30 days.
Important: Members may initiate a request to mutually withdraw Feedback within 30 days of either person leaving Feedback or within 90 days of the transaction end date, whichever is later.
Once you submit your request, it cannot be retracted or cancelled. If the other eBay member declines the request or does not respond, the Feedback will remain unchanged