Sadly, you can't. The only way is to use a third part app. There are several launchers and lock screen apps in the play store which will allow you to customize the lock screen and remove them. It really bothered me at first as well, but I guess I got used to it. My major complaint is you must have google location services on for the weather app to work as opposed to simply letting you type in a location or area code. So mine simply says no data availabe and I use a different weather app, for now.