Completely restore centOS 7 as it was on first installation ( Factory Reset)

If everything was installed via the yum package manager, you can undo previous commands:

# Get all yum commands previously run
yum history list all

# Get the details of the command
yum history info [entry number]

# Undo each command top-down
yum history undo [entry number]

Just be careful not to undo the initial system install!

For now I think it is not possible.

For the future you may consider using rear (RElax And Recover). This tool is included in centos distro , and permits reliable and easy full backup-restore operations. So that in case of disaster (hw or other), you can restore your OS in a few minutes.