Yes, you can. Access levels can be adjusted by going to the Users page under Settings.
There are four levels of access:
Personal access - practitioner can only access their own records
Own records and others' contact - as above, but can access contact details only for other patients
Clinical access - can access their own records, others' contact details and clinical notes, and make changes
Full access - can see and make changes to everything
Only users with Full access can set up other users.