grub2 - Is GRUB needed after converting an earlier dual boot system to only ubuntu system?

Well as the question says,

I earlier had a dual boot system with windows and ubuntu.Now I have deleted windows.

So do i really need GRUB now? coz actually grub does not show up but neither is Ubuntu directly booted like it would in an "always only ubuntu system"

In an "always only ubuntu system",the splash screen directly comes up.

But what I see before Ubuntu starts is a countdowsn from 5,and a message displaying "press esc to enter into menu"

Then what is displayed is something like-

"booting from (0,hd7)..." and then ubuntu starts...

So can I or do I need to remove grub so that ubuntu boots like it is an "always only ubuntu system"??

Thankyou.