An employee can cash in up to one week of annual leave each employment year. There are a number of rules and regulations surrounding cashing up annual leave, which are covered in this support article from MBIE. It's best to familiarise yourself with these rules before cashing up annual leave for your employees.
To cash up annual leave in PayHero simply create a draft pay and edit the pay for the employee who is wishing to cash up annual leave. Under 'Earnings' click the green plus and include the 'Annual Leave Cashed Up' pay item. Enter the appropriate amount of days wishing to be cashed out and PayHero will determine the rate it will be paid out at. For more information on how this rate is determined you can click the blue information button next to the pay rate.
Note that cashing up annual leave will be taxed as an extra pay, see this article from the IRD for more details.
If an employee has taken time off as leave, always use Leave Requests and the Annual Leave Taken pay item.