You are working as a Professor (not profession, I presume) and your college has a late-coming policy where anyone arriving late by 5 minutes on three occasions will lose one day of leave, correct? You have been late for 5 days and had no explanation for your tardiness. As a Professor, who is expected to teach discipline to students, you repeated the misconduct for another four days. Therefore, the decision of the Principal cannot be considered unilateral and arbitrary.
Your Casual Leave should be running from January to December, I presume. By May, you have exhausted your CL quota. Naturally, as per the late-coming policy, one day's pay shall be lost. You cannot challenge this as a matter of right. However, you can provide an explanation for your tardiness, undertake that you will not be late again, and request the authority to reconsider. The disciplinary authority, the Principal, or the Management can release it based on your request.
Please remember that a late-coming policy with a clause that you will lose one day of leave or salary, in the absence of any leave to your credit, is NOT intended to make employees lose their salary but to make them aware of their responsibility to be punctual. We should appreciate it rather than defend against it.