In the Web Portal > CRM > Payments > select the payment you wish to remove > scroll to the bottom of the page > Select Action > Undo Payment > Go.


or


In the Web Portal > CRM > Invoice > Edit > select the hyperlink payment to remove it > select the payment you wish to remove > scroll to the bottom of the page > Select Action > Undo Payment > Go.



In the App > Accounts > Invoices > Edit > Payments > swipe to the left to remove the payment. 

(Video shows adding the payment then removing it)