The Cluttered Workspace
Ubuntu (specifically the default GNOME desktop environment) attempts to make interacting with external media as straightforward as possible. Whenever you insert a USB flash drive, plug in an external hard drive, or even mount an internal secondary partition, Ubuntu automatically places a shortcut icon directly on your Desktop. While this mimics the behavior of older operating systems and provides quick access, it can rapidly lead to a cluttered and messy workspace. If you use your desktop strictly for active project files, having it littered with icons for every backup drive and SD card you connect ruins the aesthetic and makes finding your actual files difficult.
Cleaning Up the Desktop
To maintain a minimalist workspace and stop Ubuntu from automatically showing removable drives on the Desktop, you must configure the specific desktop icon extension.
In modern versions of Ubuntu, desktop icons are handled by a built-in GNOME extension. You cannot disable this via the standard system settings menu. Instead, open your main application launcher and search for the Extensions app (it is installed by default; its icon looks like a puzzle piece). Open it. Scroll down the list until you find the extension named Desktop Icons NG (DING). Do not turn the entire extension off (unless you want zero icons on your desktop). Instead, click the small Settings gear icon next to it. A new configuration window will pop up. Look for the toggle switch labelled Show external drives in the desktop. Click the toggle to turn it Off. Any currently mounted drive icons will instantly vanish from your desktop, and future drives will only appear in the sidebar of your File manager.