You are able to change this setting in the taskbar settings menu.
1. Right click the open space on your taskbar.
2. Click "Task Bar Settings".
3. On the personalization menu on the left click "Start"
4. Toward the bottom you should see "Show recently opened items in Jump Lists on Start or the taskbar."
5. Turn that setting off.
Now when you click start it should only show the program and not the sub menu list next to it. Hopefully that helps!
