Can we limit the rights of certain users?

Yes, of course it is.

There are 3 user levels.

The Administrator who is God and can do everything.

The User who sees everything except what he is forbidden to see.

The Project user who sees nothing except what you allow him to see.

In order to better understand the management in Simple CRM, I invite you to read the full explanation on this page

http://www.simple-crm.online/2018/04/how-to-limit-users-access-to-certain.html