Clear Saved Password on all servers

Hi 

when filtering the unsuccessful logins , i found 2 user have many logins failed

actually the 2 users already changed their passwords , so that we get many unsuccessful login

they didn't remember  where they used and saved their passwords 

I tried Credential manager to clear any password saved m but still receiving failed logins 

Is there any way to know where these credentials used ? " 

Mahmoud