There are three method to format nokia devises.
There is one software oxicube
which can use to format phone memory.
Try following steps this will help you.
Download and INSTALL oxicube
in your computer ->connect your phone to computer through USB CABLE
->In phone select PC suite mode ->Go to your phone memory -> delete your all unnecessary stuff.
In this way you can delete all your phone memory data.METHOD2
is no need to format your phone memory.You have to just restore factory
setting.This will clean your phone memory .Try following steps:
to menu -> click on setting -> select phone ->Click on Restore
factory settings -> press OK -> then enter default code 12345
-> then press OK.METHOD3
There is one code you can use to format your phone memory.
the code *#7370# -> then press OK ->then enter default code 12345
->in few seconds your mobile phone memory will erase automatically.
I think this will help you.