If you want to disconnect your Facebook account here's how you can do it:
- Go to your app settings in facebook (http://www.facebook.com/settings?tab=applications)
- Remove the mixcloud app.
- You will then receive an automatic mail from Mixcloud with a link to reset your password.
- In case you need to relocate the email or search for it, the subject line is: "How to reclaim your Mixcloud account"
Note that by doing this the automatic posting of your uploads to Facebook will also be disabled.