Deleting Anuual leave record

Hi everyone,

I'am new to Dynamic 365 Finance and operation, and I am handling the administration of the system for our company.

I have an employee who issued an annual leave transaction but he didn't submit it. Now he contact me to delete the record he create.

When I try to view and delete his record it appears to me this message :

"You cannot delete this transactions, it is posted already."

So what should I do so I can delete the annual leave transaction?
This is a screenshot of the message that appears to me below:
Hope I got a help ASAP.
Thank you