The ability for a sub or an employee to cancel an absence is determined by a setting in that user’s permissions. To change that setting first navigate to the employee/sub’s General Information Page and click the gray Permissions tab. Under this tab you will see the Absence Cancellation section. Choose the appropriate permission.
Don’t forget to click the Apply Changes button to save your changes.
Another reason they may not be able to cancel is if it is too close to the start time of the absence. Check the school’s Cancel Cutoff Times.