It's normal to make mistakes. Don't panic, we got you covered.
To edit payments, follow these 3 steps:
1. Choose the transaction.

2. Choose the payment you want to edit under "total".

3. Choose Remove Payment and Proceed.

Easy right? Now here's a piece of important information for you:
Adding payments is only applicable to PLUS organizations
What's next?
Posting "Draft" transactions in your Books of Accounts
Understanding how to use Chart of Accounts for precise recording