There’s been a lot of discussion about Telemetry in Windows as well as avoiding the Windows 10 upgrade. Here is the list of service bulletins we compiled and what they do. It should be noted that even when not installed, they may appear again so this will require some effort on your part. Most people will simply not bother with this but it’s great information for any tech to have at their disposal or simply for research purposes.
If you have already installed Windows and did a few updates, then head over to Control Panel > Programs and Features > View Installed Updates then go from the top to the bottom through the list to ensure none of them is installed, if you do find one installed, then uninstall it, reboot, then check for updates and once it appears right click on it and hide it.
I would suggest oup-out of them, which can be done by, right-clicking them in Available Updates List, and choosing "Hide Update".
— Ａｎｉｓ Ｍｕｓｌｉć ⣢ (@0xUID) August 23, 2015
— Ａｎｉｓ Ｍｕｓｌｉć ⣢ (@0xUID) August 24, 2015
KB2505438 (Although it claims to fix performance issues, it often breaks fonts)
KB2670838 (This update often breaks AERO on Windows 7 and makes some fonts on websites fuzzy. A Windows 7 specific update only, do not install IE10 or 11 otherwise it will be bundled with them, IE9 is the max version you should install to avoid this.
KB2952664 (Windows 10 Upgrade preparation)
KB2976978 (Windows 10 Upgrade preparation)
KB2977759 (Windows 10 Upgrade preparation)
KB2990214 (Windows 10 Upgrade preparation)
KB3021917 (Windows 10 Upgrade preparatioon + Telemetry)
KB3035583 (Windows 10 upgrade preparation)