The notification area (previously known as system tray) is nothing but the area on the right of the taskbar. Battery, volume, OneDrive, and antivirus icons usually sit in the notification area of the taskbar.
By default, Windows 10 allows you to hide icons in the notification area to avoid clutter. When you hide an icon, it will appear in the overflow section of the notification area (refer the picture below).
You can simply drag and drop an icon from the notification area to the outside of the taskbar to hide it (will appear in overflow section). When you want to view hidden icons, simply click on the small up arrow button next to the notification area.
At times, the up-arrow icon on the taskbar might go missing, and all icons (including those that were previously in the overflow section) will appear in the notification area. When you try to hide an icon by dragging and dropping it outside the taskbar, nothing happens.
If you are unable to hide notification area icons, it’s is likely because you or a program which you recently installed has configured the taskbar to always show all icons in the notification area.
Making notification area icons hide again
If the notification area icons on Windows 10 taskbar are not hiding, follow the directions given below to hide them.
Step 1: Right-click on an empty spot on taskbar and then click Taskbar settings to open Task Properties page. Alternatively, you can navigate to Settings app > Personalization > Taskbar to access the same page.
Step 2: Under Notification area section, click Select which icons appear on the taskbar link.
Step 3: Here, turn off Always show all icons in the notification area option. Turning it off will hide all notification area icons. You should now see a small up arrow on the taskbar. Click the up arrow to see all hidden icons.
As you can see in the picture above, there are options to show or hide system icons. You can show or hide clock, OneDrive, battery icon, volume icon and other program icons right from this page.