Is de-novo inquiry is admissable after submitting first inquiry report to thedesciplinary authority

You have no at all shareed any fact of the case.

You have not even indicaed if you are connected to the case and if so how?

However based at the given fact it can only be stated that "de-novo" inquiry as such is not possible.

Howver fresh Inquiry can be remanded to the Inquiry Officer if he has ot folowed the procedure. Such inqiry :-

1. will be commneced from the stage where fist irregularity is committed by the IO.
2. it can be remnaded to same or differnece IO

Please share facts if wanting to kow more.

When the inquiry report is stated to have been submitted to convening / disciplinary authority, there is no question of "de-novo" inquiry, which means "from the start".

De Novo Enquiry. De novo enquiry is generally ordered in the following contingencies: on the orders of the appropriate judicial authorities in those cases when serious procedural irregularities have crept in the conduct of disciplinary proceedings or the principles of natural justice have grossly been violated.

If the concerned employee is requesting for an inquiry from the start citing procedural lapses and serious allegations about the irregularities, then the High court may decide the petition for denova inquiry on merits 

let him share facts.