what is F System directory that suddenly appears in Windows 10  

I am very limited in Windows 10. Some time ago, I just updated my Motebook from Windows 8 to 10. Today I noted that there is certain root directory label F which I don't remenber have saw before. The worst is that I tried to browse such directory and I got the message "At this moment, you don't have permission to access such folder" (hopefully my translation from portuguese to English is close enough to the original message in English). I mean worst because I am the administrator of this workstation.
Is such "F" part of Windows or should I start think it is a bug or virus? (see the image below)

deme said:

I am very limited in Windows 10. Some time ago, I just updated my Motebook from Windows 8 to 10. Today I noted that there is certain root directory label F which I don't remenber have saw before. The worst is that I tried to browse such directory and I got the message "At this moment, you don't have permission to access such folder" (hopefully my translation from portuguese to English is close enough to the original message in English). I mean worst because I am the administrator of this workstation.
Is such "F" part of Windows or should I start think it is a bug or virus? (see the image below)

That System (F:) or System Reserved is part of Windows and shouldn't be removed. It's usually relatively small. I've found the only way is to boot to a GPARTED LiveCD and delete all partitions in preparation for installing Windows "clean", on a clean drive but that is not your intent yet.

That Smiley in my first line is a failing of this forum, replaces the colon : when posted. (F:) :) Experimenting shows the combination of : and ) inserts the Smiley. :)

This is an error. Normally a system partition should not be mounted and assigned a drive letter.
There are ways to fix this; e.g.:


http://kb.macrium.com/KnowledgebaseArticle50162.aspx

Same instance for me. Seems like due to the new update by windows.