Self signed no liability certificate

I worked in a CSIR Institute as temporary scientist under a project sanctioned from DBT. After completion of my tenure, I was asked to complete a No demand certificate form with various department head sign and I completed it. The CAO does not like me and always created problem for me. Now He is asking me to submit a No Liability certificate self attested or via email. I am no longer working there. I have asked for copies of NO liability certificate submitted by other people, but not given. Now I have put a RTI asking for NLC collected by Institutes. NLC is non-existent & nobody submitted before me. They are not allowing me to enter inside the Institute. CAO send me email saying" kindly note that your physical presence is presently not required for completing the remaining formalities at S.No. 6 & 7 above and in case of any need of your physical presence, a set date and time shall be communicated to you for the same, to avoid any inconvenience to you" Kindly advice me in this matter. Thank you very much