You can't delete the widget on the lock screen (you can remove the notifications, but not the clock itself.)
Do you mean the homescreen widget?
Are you using the stock blinkfeed launcher?
If so like Kelly said above, long press on the screen select widgets and then drag the widget you want onto the screen.
I can't repeat the steps for you because I'm not running the Blinkfeed launcher so can't use the clock widget.