Microsoft installs a number of apps by default with a fresh copy of Windows 10, many of which you'll probably never use. Thankfully, two such apps are set to disappear from that list.
As the Windows Blog confirms, the latest Windows 10 Insider Preview Build (21332) removes 3D Viewer and Paint 3D from the default app install list. Both apps "will no longer be preinstalled on clean installs of the latest Insider Preview builds. " Eventually, that should also mean the final builds we all download as part of the Windows Update process, too. However, if you do use either or both apps, don't worry. Microsoft says they will remain available for download from the Store and will remain on your PC until a fresh install is carried out.
Microsoft also confirmed that Build 21332 includes a new option to paste as plain text from the clipboard history, and theme-aware splash screens have been re-enabled. One further removal comes in the form of the Math Input Panel, which apparently nobody is using so Microsoft is getting rid of it. The "useful" tool allowed you to enter mathematical formulas by writing them out, either with the mouse, touchscreen devices, or a drawing tablet of some form.
If you'd like to play around with this latest build, then sign up to the Windows Insider Program and gain access to these pre-release versions of the operating system.