Canceling your account

1
On the  manage subscription page, unselect all your Adwords accounts or click on the cancel subscription link (which will unselect all the accounts for you). 
2
The button in the lower right will become a cancellation button. Click it.

3
A pop up field will appear asking you why you decided to cancel. Please give us as many details as you can. Click on the "Yes, I want to cancel" button to confirm.