Dear Mr Rich,
I have few question for you:
1. Did you activate the client security?
2. Did you associate your client security login with the windows login?
3. Did you enroll finger print setting for client security? - This is alternative solution for you to login using your finger print*
4. Did you tried enter with the previous password? (The one you've deleted?)
I'm afraid that you need to reformat your HDD in order to disable the Client Security password.
*Am not sure about this. Please Advice me if I'm wrong.