The default taskbar pin behavior on a pre-installed system in Windows 10 system is different from a manual taskbar pin from the users.
For pre-installed system, applications which are originally pined on the taskbar (e.g. MSI Dragon Center/MSI Creator Center/MSI Center/ MSI Center Pro/ Microsoft Xbox...), to unpin them from the taskbar, please refer to steps shown below.
1. Delete xml files:
1-1. Open file explorer and enable “Hidden items” in “View” tab.
1-2. Right-click on the file "LayoutModification.xml" and select to delete the file. (File location: “C:\Users\Default\AppData\Local\Microsoft\Windows\Shell”)
1-3. Right-click on the file "LayoutModification.xml" and select to delete the file. (File location: "C:\Users\%username%\AppData\Local\Microsoft\Windows\Shell”)
2. Unpin the application (MSI Dragon Center/MSI Creator Center/Xbox) from taskbar and reboot the system.