You can only choose to decrease the price of a task while your payment is still stored in escrow and hasn't been released.

If you wish to update your task price, follow these steps:

1. Explicitly agree on a new task price with the other party through private messaging.
2. Once you have established a new amount you may then contact Taskhelper.
3. We will modify the price on the system accordingly and return the rest of the money to the poster.

Remember that we cannot assist you until all parties have concurred on a new price. The amount should be in line with Taskhelper fees and needs to be rounded to the nearest full number

For information about increasing task price, check out this article.