Posted Sales Invoice Delete option

Hi,

In Nav RTC Page 143, if i right click i can see delete option and i was surprised to see this option, because once any document is posted then it becomes historical data and should not be deleted. 

Whereas in Page 142,  i cannot see the delete option upon right click,  I saw that both pages are of list Type, then why  both behaviour is different. I want to remove this delete option from page 143 also. Could anyone help me on this.

Thanks
John