I bought an Sony Xperia SP and when I launched the browser Chrome, I noticed there was a folder named "Sony" that I couldn't delete. Nothing in the browsers could be deleted. And to make matters worse, Chrome keeps defaulted to that folder most of the time I launched it.
I searched Google and I came upon this forum post on the XDA forums. As mentioned in the forum, to disable the folder, go into settings then apps find the app "com.android.providers.partnerbookmarks." Then click "Disable" and then "force stop." You could reboot the phone if necessary.