パスワード保護されたSEPをアンインストール

Steps to remove Symantec Endpoint Protection 11 WITHOUT knowing the uninstall password:

Click on Start -> Run (or Window Key + R if you don't have the Run menu item)

Type smc -stop. If it prompts for a password, open regedit (Window Key + R; type regedit; hit ENTER) and then navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Symantec\Symantec Endpoint Protection\SMC.
Look for the smcexit key, delete it, and then type smc -stop in the Run box again.
Note: my key was called smcexit-test or something like that, but deleting it had the same effect.

Now, navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Symantec\Symantec Endpoint Protection\SMC. Look for the smcinstdata key; delete it.

You should now be able to use Add/Remove programs (or Programs & Features in Vista & 7) to remove SEP 11 without supplying the uninstall password.

Quoted from http://andrewblock.net/2011/03/07/how-to-uninstall-symantec-endpoint-protection-11-without-the-uninstall-password