If you’ve ever fiddled with window sizes and positions to have more than one application visible simultaneously, you’ll want to learn more about that slim white bar, not remove it! What you’re seeing is “drag zone”, the drag destination of what Microsoft calls “Snapzones” and it makes arranging multiple windows on your display a breeze.
You can actually access Snapzones directly on each app’s window frame in addition to the drag bar. Add Microsoft PowerToys – a free download from the Microsoft Store– and one of the new capabilities is FancyZones, a utility that lets you create custom layouts. Even without that, Snapzones are pretty slick.
Let’s check it out, and if you’re still not sold, I’ll show you how to disable it on your PC. Deal?
WHAT IS THAT DRAG BAR?
I was moving my Settings window while waiting for a Windows update to finish and the Snapzones drag zone bar showed up at the very top:

Once that appears, you don’t actually have to drag the window to the bar to utilize Snapzones. Just move the window towards the top of the display and, upon release of the mouse button, a layout grid pops up! Prefer a keyboard shortcut? Try Windows + Z.
Here are the default layouts:

Notice that the default is to split the display vertically and to place the current app (Microsoft Edge) on the right pane.
CHOOSE A DIFFERENT LAYOUT
Prefer the current app to have more than 50% of the layout? Easy! Choose a different one by moving the floating thumbnail to the one you prefer:

When you release the mouse, the screen will lay out as indicated:

The smaller version of my web browser on the right? That’s its suggestion for the app to fill the second space in the layout. A single click expands it to fill the available space in that pane.
For best results, it’s smart to have all the apps you want in your layout already running when you jump into Snapzones for just this reason.
MORE ABOUT SNAPZONES
You don’t have to drag and move, however, you can simply hover your cursor over the Maximize button and the layout options will be shown:

With all these options, here’s how you might use it to have three apps gracefully sharing your display:

Look closely at the divider between Solitaire and the Clock app and you’ll see another secret: Once you’ve established a layout, you can click and drag the dividers to fine-tune the sizes of each window. I’m giving myself more space to play cards since the world clock doesn’t need much!
HOW TO DISABLE SNAPZONES
Not convinced? Okay, that’s fine. Go into Settings > System > Multitasking and you’ll find a number of settings and options related to Snapzones:

Click on the slider to turn OFF “Snap windows” and it’s all hidden, never to bother you again. Want to keep exploring this feature? Read through each option to consider which will work for your own workflow and interface preferences. Done.
Pro Tip: I’ve been writing about the Microsoft online universe for many years. Please check out my Windows help area to find hundreds of useful tutorials! Thanks.