Time and Expense profile employees are unable to uncheck the Billable and Reimbursable options. Is this by design?
Yes. Security settings can stop an employee from being able to adjust the billable and reimbursable status of an expense entry. You can customize the user's security profile to give this permission (under Customize Profile > Expense Entry). Generally, companies set up specific expense items with those attributes predetermined. That way, the burden is not on employees to check or uncheck such options. Check the Core Help for details.