Unfortunately, there's no option to customize the stock lock screen that way. If you're really adamant about removing those icons, your only option would be to use a replacement lock screen app from the Play Store which allows you to customize the layout as you like. The problem with that is that, last I checked, the majority of the replacement options currently available don't include support for fingerprint scanning. If that's a concern for you it's probably just best to cope with the stock lock screen as is.
You can do like I am going to do here shortly. Get rid of your Samsung phone, Chromebook and everything else with a Samsung name on it. I am tired of bing forced to have this crap on my phone. I hope the Ubuntu phone makes it to the US market soon.