On a Nexus 5 you no longer need to swipe up from the home button to access Google Now. Google Now has a permanent place on your home screen, being the screen furthest to the left. Swiping over will reveal Google Now and all of your personal cards, and of course, you can still access the service by swiping up from the home button.
For some, this feature is going to become exponentially more useful, since it's now at the ready instead of somewhat hidden. But for others, I can see how it would be annoying having it set as a dedicated home screen -- especially if you're not a huge fan of Google Now.
Removing Google Now from your home screen can be accomplished one of two ways. There are advantages and disadvantages to either method, so I'll leave it to you to decide which works best for you.
Turn off Google Now
The first method is to turn off Google Now altogether. You can do this by launching Google Now and tapping on the menu button followed by Settings. Toggle the Google Now switch to off and accept the warning that your cards will be reset. You'll no longer be able to swipe to the left to view any cards, but you'll still be able to quickly launch Google Search by swiping up from the home button or using the hot phrase "OK Google".
This does indeed remove Google Now from your list of home screens, but it also kills the functionality Google Now provides. Obviously it's a somewhat small gain for a potentially big loss.
Use another launcher
The second method is to install a third-party launcher. A launcher on Android is an app that will allow you to customize and tweak your device beyond that of the default launcher installed. Each device manufacturer has its own default launcher, but there are some really good third party launchers.
Installing a launcher such as Nova Launcher or Apex Launcher will allow you to customize not only your app icons, but it will allow you to leave Google Now enabled, while at the same time removing it from your home screen.
The added customization options with third-party launchers are a big draw to Android users, and in this instance an easy way of removing Google Now without having to disable Google Now.
So, fellow Nexus 5 owners, what's it going to be? Google Now on your home screen, or get rid of it?