Sushant,
Please refer the authorization object: I_VORG_ORD which is having fields: AUFART - Order Type and BETRVORG - Business Transaction.
Using this authorization object you can decide whom to give the authorization to release the order.
You have to create a role in PFCG (please take help of BASIS team for the same) assign transaction IW31/ IW32/ IW38 and you will find this authorizaiton object where you have to assign the order type and allow only the business transaction which user is allowed and remove *.
Value BFRE in field BETRVORG is for release of order which you have to restrict to that user after which the user wont be able to release the order.
Please follow the above steps and do tell if you have any further clarification required.
Hope it helps.
Chin2.