Can I safely delete .facebook_cache folder if I don't have a Facebook app installed? I have noticed that there is a folder named .facebook_cache in /storage/emulated/0/ 

I have never had the Facebook app or the Facebook Messenger app installed on the device and I don't intend to. At first I thought it must have been put there by the Facebook website, which was concerning, or been set up as default by the Android OS. After reading around I assume it was imported as a backup from the Google cloud from an earlier device which had the app installed.

Can anyone confirm the reason that it exists on this device and if it is okay to delete the folder without causing any issues?
Quoting from Mathew Read's answer here


  Cache is temporary files. One example might be thumbnails for contacts in a social media app. These can be cleared without any major effect — the app can just download them again when it needs to — and if space is low the Android OS may remove cache files itself.


You don't even have the app installed , so it can do no harm

The reason for it being of likely the Google Backup, since you never installed the app 

You can also use the SD maid app mentioned here, which I find very effective in removing corpses and cleaning system How to clean up related files from deleted apps?