I decided I did not to use Start 11. After I uninstalled it my task bar remained small not returning to the Windows 11 default. I reinstalled Start 11 and changed the task bar to medium size then uninstalled Start 11 again. My task bar is not the windows default one. You need to fix the uninstall process and remove all remnants of your software modifications from my computer.
If you have set the taskbar back to medium you should have the normal taskbar back.
If you have changed the position of the start button to be on the left then you can put this back using the usual OS settings for this. The option in Start11 is purely designed to make it easier for you to change that.
Future updates of Start11 will have the option to reset the taskbar settings back to default on uninstall if you wish to remove all your user settings.