You cannot.
Only the seller can but are not obligated to doing so as they have already been charged fees because you purchased.
Many sellers will proceed with an unpaid case to get their fees credited back and buyer gets a strike.
Two or more strikes will limit your buying on eBay.
You could pay for the item and resell or gift it if you no longer require it.
If the seller agrees to sending you a Mutual Cancellation, make sure you agree to it so they get their fees back.
