You can decide what operations the client can perform and what operations he/she should not be able to perform. To edit the client’s permissions for operations:
Click the
Permissions icon on the Client Home page. The Client permissions page will appear displaying the list of permissions for all available operations: 
In order to allow (forbid) the client to perform a specific operation, check (uncheck) the corresponding checkbox.
IMPORTANT
Allow performing operations of managing crontab and system access only to trusted clients as these operations must be performed with great care and can have most serious effects on the system.
When you are done editing, click OK.
NOTE
When you revoke certain permissions granted to the client, these permissions are also revoked from his/her customers.