Win10 has an option in the recovery options menu to restore the machine back to its original state.
This option is available for 30 days after you perform the update to Win10.
See
http://www.thewindowsclub.com/rollback-from-windows-10I would recommend doing a backup of the machine
first using Macrium Free.
http://www.macrium.com/reflectfree.aspx[Very good Backup Software. Free version will only restore to original machine but is fully working otherwise. Have used it and is very good software]
The win10 Rollback has been reported to not always work smoothly. It did work for me recently with no major problems. Hence the backup for insurance.
Macrium will perform a full disk backup which will allow the disk to be restored to the original state if there is a problem.
Do not run any 'fixes' the are supposed to automagically make things 'work' as they cause more problems than they fix.
If you have any questions please ask.