This is caused by the Teacher being assigned that class for part of the year.

To remove the teacher from a course for a future term, navigate to:
  1. Academics > Scheduling > Requests and Schedules > Set Section Info
  2. Change the term to the next term of the year
  3. Locate the Course Section in question
  4. Check the Teacher Field
  5. If the teacher is not the correct teacher, click on the name to choose a new teacher from a drop down. If not, repeat steps 2-5