Can I enable or disable team members from creating or amending their own timesheet?

Yes, users with an access level of Location Manager, System Administrator and Advisor have the ability to enable or disable team members from creating or modifying their own timesheets. 

Removing a team member's permission to create or modify their timesheet means they cannot:

• adjust their start or finish of shift and break times if they forgot to clock in or out on time,
• create a timesheet for a shift in the past they didn't clock in for.

This setting does not affect the ability of a Team member to clock in for an unscheduled shift.

Read more at Enable / disable team members from creating their own timesheet.