Unfortunately, the sent letters cannot be edited or deleted.
Our original idea is to make it closer to real life experience - once you posted a letter, you can't take it back; and also, to avoid confusion from the receivers - they will receive notifications once you sent the letter.
We understand that it may cause potential problems to users - as there are accidents, so we have added a "Confirm to Send" pop up box before you sending out the letter. To enable it, please follow these steps.
1/ Go to My Profile (rightest tab, bottom menu)
2/ Go to Settings (top right corner)
3/ Scroll down to Pen Friends
4/ Turn on Confirm before sending the letter
Meanwhile, is it possible to send another letter to your pal to explain?