Disable password logon as an option - but still want ability to use the Change Password feature with Ctl+Alt+Delete

Hello,

We are using H4B with PIN to logon to our desktop.  We remove password login as an option so the only option is PIN.  However, we still want users to be able to Change their passwords through Ctl+Alt+Delete because they do still user password for other applications and services in our organization.  How that be achieved?