NTA communicates online with its Candidates through the Registered Email Id and Mobile number. So it is important to have an active Registered Email id so as not to lose out on any important information. But having said that, if you have deleted the Email, nothing can be done about it now. Your admit card is usually sent to the registered email id once you login to the official website for downloading your Admit card. Apart from that, your login credentials for NEET website will be in your Registered Email id. But again all this information will also be sent to your Mobile Number. So you should be fine. This will not create any issues during admission. But during Counselling, should you get a seat, the allotment letter will be sent to the Registered Email Id. You need to download the allotment letter from there and carry it for document verification adn during college admission. So this is where you will face issues if you do not have Registered Email Id active. And without the allotment letter, you cannot take admission.