@garvit,
Here by ‘karan’ zoozoo perhaps means ‘reason’ and not a person’s name ‘Karan’.
What garvit has written is almost correct, with a couple of changes:
“Sir,
Please allow me to leave office daily at 5’o clock for one month, as I have to reach for the drum practice by 6.
Thanks”
Please also note the difference between ‘practice’ and ‘practise’. Google for it.