To change Tax Regime in Timelabs Payroll, first go to Salary Structure menu -> click on Employee Setting page. On next page click on 'Set TDS Regime' button:
It will show all employees list with their currently set TDS Regime.
From above window, select the employees whose TDS Regime you want to change, Set Regime type from right side dropdown and click on 'Set' button. At last click on 'Update Selected' button.