An office version is preinstalled on my new laptop.
If I delete them and then reset the laptop to factory settings, will Office be back?
It depends on how this version of Office got on the laptop. If Office is part of the "total package" of software that was loaded onto the laptop using the boot CD (ie the CD-ROM included with the laptop), then yes. If the office software "only" was installed by the provider of the laptop with a separate installation, then resetting to the factory setting will "throw down" this installation and is gone.
The Office version was already installed when you bought it.
Then (!) It could be that with the reset the original installation is restored. But this can't be said with certainty from afar. Because "factory setting" means: The way the computer left the factory… And Office was not yet forced to do so. Do you have a system CD (or several)? It may be better to "re-create" everything.
