college and work conflict

im in a situation, i just got my timetable for my college course and i start this monday, i told my work that my availability has changed and that i can no longer do shifts on certain days, however my boss hasnt changed the shifts that i was scheduled for this week, what should i do? Theres also the problem of i want to quit my job and focus on my education as that is more important to me as i wouldnt financially struggle and my parents said they would give me money whilst im still in college as long as i did all my work for my course.