Disable taskbar preview in Windows 10

I used this method:

In:

HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Taskband

In the right-hand pane, right-click and choose New – DWORD (32-bit) Value . Give it the name NumThumbnails. You’ll create the 32-bit DWORD whether you have 32-bit or 64-bit Windows. By default, it should have a value of 0, which is what we want.

@anadrol's answer is correct and doesn't involve installing any potentially unwanted software. Here's a powershell answer:

New-ItemProperty HKCU:\Software\Microsoft\Windows\CurrentVersion\Explorer\Taskband -Name "NumThumbnails" -Value 0 -PropertyType "DWord"

Then restart explorer:

ps explorer | kill

Thumbnails will be replaced with a window list:

7+ Taskbar Tweaker can disable taskbar thumbnails. It's very lightweight and supports a lot of other useful customizations.