QB Issue Resolution:

Go back to your saved payroll. On the “Enter Payroll Information” screen, for each Employee Name that is highlighted in yellow, select the name, do a right mouse click, and select “Revert Paycheck”.
This should cause the paycheck to reset itself to what it was before you saved this payroll to “Finish Later”, and taxes should be recalculated.

Resolution for Issue 'how to I cancel an unscheduled payroll that I started but didnt complete?' available: Yes (Solved).
Source: Intuit Community forum.

how to I cancel an unscheduled payroll that I started but didnt complete?: this issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the issue yourself by looking for a resolution described below. If it is a complex issue or you are unable to solve the issue, you may contact us by clicking here or by using other support options.

Support for Payroll
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Error Recovery for Payroll [Canada]
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