In some cases you might need to cancel your offer even after you sent it to a buyer.
To solve this, you should use Withdraw project dialogue.
How to withdraw your project
You are able to withdraw your project if it is not confirmed by a buyer. So only sent and not confirmed offers are eligible for withdrawal.
Click on "Withdraw Project" button in order to cancel this offer.
What happens after you withdraw your project
Buyer won't see your project in his dashboard and won't have any access to it. This is quite useful if you want to make some changes and re-send a new offer.