I am not sure I understand it either.
It sounds that you do not have LDAP authentication but another type of single sign on.
One way to check that is to see if you have External Authentication box in Administration > Users - user properties.
See the screenshots in screen shot.doc which Senthi has attached to
If you do just create user ID's so that the box is not checked.
If you do not have that then try to create a user id which does not exist in Lotus notes.
Do you have https in the URL when you are in CA PPM. If you do then it might be possible for those users to access CA PPM if you enable http access in CSA for them.
You might want to mask the real names of the users when you post here unless you have their consent not to.