You can add/remove staff access to the CRM / as below:
1.Add Staff Member: Go to Settings ( bottom cog on menu on left hand side) and go to Staff Members and click 'New Staff Member'Watch this quick walk through for adding New Users
2. Remove Access
(a) Select Settings / Staff
(b) Turn button to 'Inactive'
3. Delete a user and allocate their data to another member of staff ( e.g. manager)