Make sure the battery fully charged Backup all your important data Power Off Your Sony Xperia Z3 Tablet Compact Press And Hold Volume up Key +Power Key Now You Will see a Android Robot on screen Select " Wipe Data / Factory Reset " Option By Using Volume Key . Press Power Key To Confirm. Now Select " Yes ----- Delete All User Data " And Confirm Select Reboot Option And Wait That is all ! - See more at: How To Hard Reset Sony Xperia Z3 Tablet Compact Step By Step Tutorial