[pnw]

You can turn it off without resorting to a local account, although it's non-obvious.

GPEdit -> Computer Configuration → Administrative Templates → Windows Components → BitLocker Drive Encryption → Operating System Drives → “Choose how BitLocker-protected operating system drives can be recovered”

Repeat for other drives.

[g-b-r]

I imagine you have to re-encrypt the drive after that, though, for it to have some real effect

[smileybarry]

No, you can just revoke and regenerate the recovery key with `manage-bde`.

[vel0city]

No, the actual data encryption key doesn't need to change unless you're very paranoid. The backup key and your normal key is just to decrypt the data encryption key.