Can you elaborate your question? Does the users that are changing others users passwords have SUPERVISOR access in ODI? If yes, then there is nothing that you can do, since SUPERVISOR access may change others passwords.
You could give developers just the DESIGNER profile (in the Security tab), uncheck the Supervisor Access Privileges checkbox, and change the password of the SUPERVISOR user. That would probably work, but if you have people in your team actually changing other user's passwords technical solutions will not be enough.
Best of luck with that, Marco