Hi @RajeshK
The Options Chain overlay is in-house built by Dhan team. The undocked order is window is part of the tradingview library and there is little control of us.
Alternatively, you can use dhan standard order window (click Buy or Sell from the top menu), this works exactly as per your requirement. Read more about dhan standard order window on tv.dhan.co here 
Introducing: Dhan’s Standard Order Window on TradingView (tv.dhan.co) with Margin Requirements