As from my personal experience,i once tried but coudn't find any delete option in my paypal account to do it.
As far as i know only the person receiving the payment can delete an e-cheque
I'm verified and have been a premier member for three years now. Maybe I need to renew but its a pain in the arse that I suddenly can't do instant transfers.
Could be your credit card details need updating,if you have had a new card sent to you it may be your old number is still on your paypal account details....happend to me when barclays sent me a new card.