There are a couple of things to be customised here.
The table headers have to be slightly changed For example, Item Name to Item, Quantity to Qty
The currency must not be printed in the items table at all. For example, the Rate column must only print 20.00 instead of AED 20.00; and similarly for Tax Amount as well as Total Amount.
For the Sales Invoice Item form, can you try changing the relevant fields from currency type to something else, say float? I don’t know if this will also change the sales invoice report or not. Otherwise custom fields could be tried.