Well I suggest you not to weat full sleeve shirt in any of the government enterence exam including JEE mains as their security check is a bit strict but it also depends upon the exam center as in some centers the staff members are a bit linient I remember in my center they didn't allow shoes, full sleeves shirt or top, socks and they even asked me to remove my watch and earings so to be on the safe side avoid such things. 

Good Luck!!