Access Your PayPal Account
Whether you are a buyer of seller of products and services on the auction site eBay, to cancel a payment you will need to access your PayPal account. It is a dead easy step. You just have to put in your email account details that is registered with the PayPal and in the password section enter your password. Always make your password, which easy to remember, but it should not some common word, as it is likely someone else can access your account and change your details. If your account is hacked you cannot access your account with the email and password you have provided. So just try to save your password. Do not give your details to another person to access your account. If you think that your details have been compromised, just contact the helpline of the site, or change the password immediately. Also, try to change some other basic information like security question if you are suspected of them being compromised as well.
Cancel Payment from Payment History
After you access your account, which means you are logged into your account, go into history tab. From the history tab you click the payment history. It will show you the most recent payment you have made, including the history of other payments. From there you click on the payment you want to cancel and press the cancel tab. The payment will be cancelled. The process is same whether you are a buyer or seller. Also, you are not required an addition information or cause of cancellation of the payment at that stage.
Communicate to Trader
Once you cancel your payment, an automatic message is sent to the payment party, whether he/she is a seller or buyer. It is still advisable and a good gesture that you should contact the person who has made the payment against purchase or selling of a product. This will finish your task of the payment cancellation, if your email you explain a bit to the payment party why you have cancelled the payment, you are most likely not to be contacted again. It will also prevent you from getting negative feedback.