As far as I know, it is best to consult the relevant departments of Xiamen University or consultants and other professionals to ensure the most accurate information and guidance for the specific requirements of changing majors in Tan Kah Kee College. Generally speaking, schools will have certain requirements and procedures for demoting majors. The following are the common situations and suggestions for general demotion majors:

1. Understand the relevant policies and procedures: First, you need to understand the policies and procedures of the school's major demotion. You can check the school official website, student handbook or contact the relevant departments of the school to clarify the ways and requirements for applying for demotion.

2. Understand the requirements of the target major: understand the requirements and conditions for changing majors, including subject setting, credit requirements, course requirements, etc. To ensure that you meet the entrance requirements of the target major.

3. Consult a counselor or related department: According to the requirements of the school, you may need to contact a professional counselor or related department and ask them about the specific matters and handling procedures of major conversion.

4. Prepare relevant materials: according to the requirements of the school, prepare the application materials required for demotion to major, including academic transcripts, personal statements, letters of recommendation, etc. Ensure the accuracy and completeness of materials.

5. Application waiting for notice: submit the application according to the time and method stipulated by the school, and then wait patiently for the school's review and notice.

It is worth noting that the specific requirements and processes of each school may be different, so I suggest you directly consult the relevant departments or counselors of Tan Kah Kee College of Xiamen University for accurate guidance and help.