You can takedown your releases directly to your account.
If you want to make a "Takedown a Release" you will need to submit a support request.
Do this by clicking the 'Support' link from the release toolbar into to selected release.
Select the option " I want to delete my release from all stores"
Please tell us why you want to delete this release.
Note: The release will usually be taken down within 3 to 5 days, however some stores may be slower to respond.