Delete Periods?

I just started the Depo shot on Sept. 17th, about a week after my last period ended. I haven't started my period yet but I did spot a little yesterday. I had sex the day after I got my shot & the condom broke so I took a pregnancy test this morning to rule that out. It was negative so I'm assuming the late period is due to my body adjusting to the Depo. So anyway, Glow says that you can delete periods but every time I try, the delete button is grated out and all it will let me do is push "My period is late". How do I delete it so I can start it myself when I do actually get my period?