Re: is there any way to uninstall cortana?
What "machine" are you referring to? A laptop? A full desktop?
If you're referring to a PC, simply bring up your start menu/screen, then type "Cortana" - this should bring you a choice to click on "Cortana & Search Settings". Clicking on that will bring you to a page where you can disable Cortana - it's the very first toggle switch in there.
Should you have further questions, please don't hesitate to create a Windows Central account and to respond to this thread.
Windows 10 has dramatically improved the speed of my three-year-old laptop, but I've got a 2.4 GHz quad core intel i5 processor and 8GB of RAM.