I am 14 years old I am having annual sports day next week during my periods and I am taking part in it and I want you to suggest me how to postpone my periods or stop my periods for one week.
Postponing your periods can result in hormonal imbalances which can lead to problems in the future. You are young and should not try such things, especially interfering with the normal hormonal cycles of the body.
However, if you are interested in postponing your menstrual cycle, you could simply use oral contraceptive pills. These are hormonal pills that regulate the menstrual cycle. They are meant to be taken after the first five red pills (i.e. the pills to be taken during your periods). This will help postpone the menstrual cycle by about a week. Once you are done with the postponing of the cycle, stop taking the pills and you will get your periods within a week.
I would recommend that you don’t take such measures. It is important for you to understand that any measures taken to interfere with the normal cycle can cause problems. Best of luck.