If you want to remove your negative feedback then follow the advice that has already been given and revise your feedback when you get the chance to do so.
Just in case you make any further purchases on the site and problems occur the first option should always be to send the seller a message via My eBay and see whether the two of you can resolve the matter amicably without the need to even get eBay involved. Leaving negative feedback should really only be done if every attempt to resolve the matter amicably has failed, examples of which would include cases where the seller has been awkward, obstructive, verbally abusive, and/or has handled the case in a manner which gave you no second option but to escalate an eBay case in order to force a refund. Any of those things would be a justifiable reason to leave negative feedback, but if you get in touch with the seller first and you get the impression that it may well be possible to resolve the matter amicably with the seller then hold off of leaving any feedback until the matter has been resolved. When you're feeling calmer you can then make a balanced decision as to what feedback to leave for the seller if you still want to leave feedback. Leaving feedback when you're feeling calmer, as opposed to when you're feeling angry, is the best way to go about leaving feedback if you do intend to leave feedback in relation to a transaction.
