Disabling standard tabs PO Screen on portal (WebDynpro)

Hi Experts,

I have a requirement in which for a specific Purchase Order, on click of EDIT button on PO POWL all the standard fields ( on all tabs ) should get disabled and only possibility is to delete the line item and SAVE.

I am trying to implement below:

We have implemented the standard BADI WD_BADI_DOMODIFVIEW.

I am new to webdynpro programming, I need help in getting the Root context node and using the context read all fields and disable all fields.

Is there any better way of achieving this requirement ?

Regards,

Vishal