I'm adding this answer because, judging from some of the comments, it is not clear to all that Windows 10 offers two separate interfaces for uninstalling programs, and that editing the registry is generally not required to remove an entry from the programs list. When there is a problem uninstalling an application, the newer "Settings" interface does not currently provide the option to remove the entry. However, the older "Control Panel" interface (which is still easily available in Windows 10) does allow removal of an errant entry.
Yes, strictly speaking, this does not answer the OP's question about where the registry entry is, and about using the newer Settings-based interface, but it may offer a simpler solution that more people (including myself) are looking for when they land on this question, and that may not be obvious on a quick reading of previous answers (even though some do explicitly mention Control Panel). And, it DOES directly answer the Subject Line of the OP's question.
Here are screenshots to emphasize the two methods.
The older Control Panel, "Programs and Features" interface (available from the Windows Start menu, Control Panel, then select Programs and Features) allows removal of the item:
The newer Settings, "Apps & Features" interface DOES NOT offer to remove the item:
Get-Command -Noun Appx*