Period Log Issues - Technical

I'm having trouble fixing my period log. I went to edit the length of my most recent period and somehow ended up marking my next period to start way early which is throwing off my other predictions for fertile days in my cycle. I'm on cycle day 7 right now and it shows that my fertile window started at cycle day 3. I can't seem to highlight and delete the future period log but it's still affecting my outlook for the rest of my cycle.