Period tracker

Mary • I am 31, happily married, and have two beautiful boys, baby #3 is on the way. Due in the fall🍂🍁🍃!
I am fairly new to glow and accidentally marked that my period began today, which it did not. I am not due to start until the 18th, but it won't let me delete. Will I be able to delete it in a few days? I am TTC so I am trying to keep things in order. Thanks!