How do you delete the very last saved slot plzzz help me. My game one get..

It sounds like your game is severly damaged. It might be physical damage, in which the only solution is to buy a new game. If you can make it to the title screen (not the menu, but the screen with just Zekrom) press Up-Select-B and delete the save file (you cannot delete a single save, only the whole game). If the problem isn't physical damage it was caused by hacking. Do not hack anymore.

To delete the saved game you have on your Pokemon White game, you must go to the screen where it shows the picture of Zekrom right when you start up your game. Then once you are at that screen, press and hold the following buttons on your DS:
Up
Select
B
You must press all of those buttons at the same time. Once you have done this you should come up to a blue screen. Once you are at the blue screen it should have slow text and ask you if you want to restart your game.

I hope I helped. If I did, please rate.

If you press Up, Select, and B all at the same time on the title screen, you should be given the option to erase your save data and restart your game.