It is possible to delete a from the red Delete button in the detail of each payment.
Also, you have the possibility to delete the 'Payment Operation', intended as the money inflow or outflow. A payment operation represents the monetary transfer that happened.
You can delete a payment operation by clicking on the red bin icon that you find in the payment detail by scrolling down in the payment history.
Deleting a transaction is an action that cannot be retrieved. Please be careful before deleting anything because you won't be able to retrieve those data anymore