Easy. Head to the 'My Accounts' section in your Profile Page. Tap on your Savings Account.
Select Change UPI PIN.
You'll arrive at a screen monitored by the National Payments Corporation of India
Follow the simple on-screen instructions and you can change your UPI PIN
Please note: If you reset your UPI PIN, the UPI PIN for any connected Federal bank accounts (including other partner neobank accounts), will also change.