All those who tried to install or who have installed Win11 you now have a new program called Windows PC Health Check now installed.
Uninstall it (add/remove programs). Then go to your Program folder and uninstall all the new Programs Windows left you. Just right click the Icon and uninstall. Then turn off automatic system updates. But do remember to check for updates manually once a month and only pick the ones you want/need.
Those who got the msg saying your PC doesn't qualify for this upgrade it is because your motherboard doesn't have the TPM chip or it hasn't been activated which is the chip that Windows uses for its new and improved security platform. The majority of boards don't have this so your PC isn't finished. Many of Intel's new boards as in 2021, don't have it either.
I have Win11 on a notebook, I uninstalled all the new programs and I turned auto updates off and to be honest its ok it doesn't bite it just looks different. I'm in my 70's, I like change so I adapt.
Don