Closed groups open themself

Hi people

Is there a way to get in contact with booking somehow??

How can I cancel a booking of a guest?? Or can only a guest cancel his reservation, but I can't??

I have several group of rooms, I close them but then somehow they are open again and people make reservations which I do not want. First I would like to know why they are suddenly open again and second how can I cancel these reservations that came in?

Thxs for your help, Thomas