Hi Amit,
CA APM does not fully support multi-tenancy. For the Metric Browser and Dashboard Console you can define domains. An agent is associated with exactly one domain.
On the Home Dashboard and Application Map domains are not considered.
The best and most granular option is to use CA EEM which is a free add-on and can be downloaded from the CA Support Download Center along with other APM binaries. It gives you the most granular control over user permissions and can manage user by itself or link to an existing directory for user authentication.
Please consult the APM Security Guide, comment on sections that are unclear for our doc team or ask follow up questions here.
Ciao,
Guenter