Uninstrument boot drive

I've unencrypted my primary boot drive and want to uninstrument it to remove the pre-boot authentication.

Running pgpwde --uninstrument --disk 0 --passphrase "..." gives me an error reporting "already in use".  Is this because I'm running pgpwde from the disk I'm trying to uninstrument and am booted from?  I'm also the only user reported by pgpwde on this disk.  I believe our IT can recover our passphrases so they must also have a key.

Thanks for any help.