A deduction can be disabled (suspended) or re-enabled for an individual staff member by bringing up the staff member's Personnel→Modify Staff→Payroll→Deductions screen, locating the Deduction you wish to suspend, clicking the Properties button for the deduction to open it for editing.  A "Suspend Deduction" checkbox can be located at the top left of the 'Modify Deduction' screen.  Checking this box will disable/suspend the deduction for this employee.

To suspend the Deduction for the staff member, check the "Suspend Deduction" checkbox and click Save.

To re-enable a suspended Deduction, uncheck the "Suspend Deduction" checkbox and click Save.