Hi TTCL_Microsoft,
to disable BitLocker, you will need to have the recovery key or the password that was used to enable it. If you don't have either of these, you will not be able to disable BitLocker and access your files. For more details about how to find your recovery key, please see Finding your BitLocker recovery key in Windows - Microsoft Support.
Important: Microsoft support is unable to provide, or recreate, a lost BitLocker recovery key.
If you have tried using the "manage-bde -protectors -disable C:" command and it didn't work, it's possible that the volume is still locked. You can try unlocking the volume using the recovery key or password by running the "manage-bde -unlock C: -RecoveryPassword [password]" command in the Command Prompt. Replace [password] with the actual recovery password.
Kind regards,
Lei