When you are selling, ensure you have your bidder blocks in place.  These can let you block bidders that have more than 1 UnPaid Item strike in the last 12 months, or you can vary the time to more than 1 strike in 6 months, or as short as 1 month.  This block will certainly stop serial non-payers from bidding on your items so long as at least 2 of their sellers do the UPI thing with strikes issued.

If your non-paying buyer is the one that left you feedback stating they misunderstood pickup then I would not ask eBay to remove the feedback.  The reason is that if it gets removed the +ve rating may stand and the comment replaced with "This comment has been removed by eBay", which may leave potential buyers wondering why it has been removed.  The comment as it stands says nothing bad about you.  You can post a reply to that feedback saying something like "sorry you did not understand the pickup process".