Can I delete a holiday request that I've already sent?

Yes, you can, as long as you haven't used your days off yet.

Se podrá eliminar el día de vacaciones tanto si ha sido aprobada (clicando en el día en tu calendario, te saldrá la ventana donde te dará la opción para poder eliminarlo) 

You can delete a holiday day even if it has been approved (simply click on the day in your calendar, and a window will appear with the option to remove it)

as well as if it is still pending approval (in your "Holiday request history" section).

 

A cancel request will be created and will be added back to your holiday balance once your administrator approves it, allowing you to request the days when needed.