Instructions
Navigate to the Mojang account migration page. (See the link in Resources.)
Enter your Minecraft username and password, and then click "Migrate Account."
Click "Log in." Enter the email address and password for your account. Click "Log in" again.
Click "View Account Settings" under My Account.
Click "Learn How" in the Delete Account section. Select "Request Account Deletion."
Check your email inbox for a message from Mojang. Click the link in the body of the email. You'll go directly to the account deletion page.
Enter your password and answer your security questions. Click "Delete Account."