From within a client file (its probably best to use a client file with a penalty so you can check the formatting easier), click Tools > Letters > Manage Standard Letters 

Choose Standard Client Letter and click the Edit button, scroll down to the line you want to remove and delete it, then click the magnifying glass on the toolbar and view the letter to make sure the formatting didn't get funky when you deleted that penalty line. 

Once youre satisfied with how it looks, click the X in the corner of the letter and choose to Save changes.