Q: Locked notes can be deleted without prompting for the password.So, here there is chance of someone deleting the locked the notes intentionally.

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Is it possible that locked notes is not asking for a password because you are using Touch ID?  See:

Keep your notes secure with password-protection - Apple Support

especially the section:

On your iPhone, iPad, or iPod touch

You can create a password in your device Settings or directly in the Notes app. Then you can turn on Use Touch ID on your iPhone or iPad, so that you can use your fingerprint to unlock your protected notes.

No, you can delete locked notes.

I'm not sure why the OP thinks it's wrong, but the point is you can, so it's behaving as intended.