Green thing in center that i can't remove

I wrote an How-to-do-instruction in this older thread: Re: Starting with Illustrator, problem with background and artwork

Or, if you want to hide the marks and the rulers in an existing document, just open the Artboard Options dialog (double click the Artboard tool in the Tools palette or use the Artboard palette flyout menu) and disable all options in the Display section. Then go to View > Rulers > Hide Video Rulers.

That looks like crop marks template items including bleed.  You should be able to a.) deselect it in your preference file ( Illustrtor > Preferences ) and b.) look at your layers and see if there is a layer that has those green items on it.  If so, you can turn it off and lock it ( deselect the eyeball and select the lock on that specific layer ).  You could also take a look at your Page Setup in the Print dialogs.  You might be able to deselect trim marks there as well.