Would you tell us which mobile Reader app you use? Is it Acrobat Reader for iOS, Android, or Windows Phone?
There are FAQ documents for Acrobat Reader for iOS and Android.
Please note that you are not able to perform any file operations (rename, move, delete, etc.) in "Recent". You need to switch to "Local", "Document Cloud", or "Creative Cloud" (if you are signed in) first.
Hope this helps.