I am an admin in the group 1.d4 Nf6 Indians. The super admin has quit and I am not able to manage the group. I have asked for volunteers but it seems I cannot promote anyone to admin. Please advise.

Find Kohai, explain to her what has happened to your SA.  Ask her to make you the SA for the group.  

 That is correct, by messageing it her.

That, or, find her online when she comes on..... She did it for me with team Oregon when we lost our SA..