You can clean junk data from mobile:
Clear App Data
Some apps store a lot of temporary files on the internal memory which can build up over time. Apps like Facebook, Google Maps and web browsers are particularly bad for this, due to the massive amounts of data they have to manage on a regular basis. Clearing out these temporary files can free up a great deal of memory for your smartphone and can be done by following these simple steps:
Go to Settings
Select 'Applications'
Select 'Manage Applications'
Find the application you wish to clear and press on it
Press the options for both 'Clear Data' and 'Clear Cache'
Another simple way to free up storage space is by deleting all the log files in the device memory.
Just dial *#9900# on the tablet and
select option 2 “Delete dumpstate/logcat” in the prompted menu.
Hope it helps you!!