CKEditor4.0, how to remove style attribute of <img> after uploading?

Question

I uploaded an image to my server. Now I want to remove style attribute of <img> because I don't want inline styles like height and width, just initial size.

So, is there any method to execute in

window.parent.CKEDITOR.tools.callFunction( funcNum, fileUrl [, data] ) 

Answer 1

https://docs.ckeditor.com/ckeditor4/docs/#!/guide/dev_disallowed_content this is what I need,thanks to @Saineshwar