We are sad that Gyazo couldn't do what you wanted. We can help you with deleting your account.
Please note that these instructions are for free users. Pro users should downgrade their account to free first. After downgrading your account, please follow the steps below. To downgrade your account, please see here.
In order to delete your Gyazo account, please follow these steps.
1) Go to your setting page when you are logged in.
2) Click the "Delete Your Account" button at the bottom of the page.
After you click this button, all of your uploaded images from any connected device will be deleted from our server permanently.