If you wish for your account and all your information to be removed permanently, you will need to contact customer support and answer a few security questions to ensure that you are in fact the owner of this account. Deletion of an account with purchases is not possible for security reasons.
You can submit your request here.
NOTE: This action is permanent and not intended for users who wish to continue to play or return to play Warframe. This is due to the fact that we cannot guarantee that you will be able to sign up for Warframe again with the same email address or username associated with your deleted account.