Being a 22 grade officer, you can't demand the PM to resign.
To do that, you have to resign, wait for 2 years, and then do the politics.
Only Supreme Court has this power, that too if the "trial" occurs, or in the inquisitorial proceeding it becomes crystal clear that PM has broken the law, the punishment of which results in disqualification. Even EC can't disqualify directly, it can only de-notify a member of assembly. Ye alag baat hai ke PM ki post automatically khatam hojaegi if a person doesn't remain a member.
IKs demand was to accept this offer of "transparent inquiry on 2013 elections" only on one condition, if PM resigns and Gen RS helps him in sending this message across, which for obvious reason, RS denied.