Yes, to open an existing pledge, click on a Due Amount from the constituent's Pledges tab or the main Pledges grid.

To delete a payment, click on the trash can icon in the last column of the pledge schedule grid to delete a particular payment due. Type "YES" to confirm that you want to remove this row and click OK or click Cancel to keep the row. 

You can also click on the Delete Outstanding Pledges button to delete all unpaid pledge payments that are due.

One or all pledge payments can also be written-off if you prefer to maintain a record of the pledge but show that the amount due to changed to zero. View the article "How do I write off pledge payments?" to learn more.