You will probably want to set the individual tax exemptions as high as possible eg. 999999999.  On the employee ledger, there is a tax tab.  Enter that number in the first line.  It basically sets the lowest amount that can be made before taxes are calculated.

Make sure on the same tab you uncheck the EI and CPP so they will not calculate.  I have not tested this concept in many years, but I believe that is the way to stop the calculations.

The only other option would be to not use the Payroll Cheque Run feature and do each cheque individually in manual mode.  However, if you are using a version from recent years, unless you are paying for payroll updates, there is no way to run the Payroll Cheque Run.