Each college might have its own policy regarding subject changes after confirmation. Some colleges might allow changes within a specific window or under certain conditions, while others might be stricter.

If there are seats available in the Psychology bifocal subject combination, then changing from Mathematics might be possible.

Contact your FYJC college as soon as possible. Explain the situation (mistakenly choosing Mathematics instead of Psychology) and inquire about the possibility of changing the subject.

Request to speak with the principal or admissions department to discuss your situation and explore options.Be prepared to show any documents that support your case, such as your original application form where you indicated Psychology.

I hope it helps!