This is not very clear, without seeing more of the text before it. But, to "ditch" something could mean to leave or abandon it. And "orientation" can be an introduction to something. For example, someone could have a college orientation meeting to attend when they start at a new school. If they ditch the orientation, that means they are going to skip that meeting, or leave before it is over. Does this explanation make sense in the story you are asking about?