can i give jee main although i have taken admission in any enginering college????????

dear devdatt 
yes , sure , but if you are in iit ,. then you are not permitted for changes of trade . 
in any other engg collge , that will not matter in jee attemption . 
so, if you fulfill the criteria of minimum percentage and max . no of attempt , then go ahead with attemption 
regards 
kindly approve