To modify it through the app,

1. Tap >Funds and tap Transaction History.
2. Under Withdrawals, select the request you want to modify. 
3. Tap Modify, edit the amount, and tap Update.

To modify it through the web,

1. Click the dropdown beside Funds on the top right panel of the web.
2. Click Deposit/Withdraw History.
3. Under Withdrawal, select the request you want to modify.
4. Click Modify, edit the amount, and click Modify Request.

Note: 

• You can modify your withdrawal request only if it is in a pending state
• You can modify your withdrawal request before 9:00 pm