Work PLEASE HELPP

So Friday I had an interview, and it turned out to be the complete opposite of what I thought it was going to be. She didn’t even ask if I wanted the job or anything she just said okay I will see you here at 9:30 sharp on Monday. But I don’t want the job and I have another interview at 11 on Monday she meant well but it was a no. Idk how to tell her I wont be there on Monday or I decline the job PLEASE HELP😫 I know I should have just settled it then but I am a big push over I hate telling people no