"resetting a used device"

[clnn]

hello!

i'm new to the blackberry community, since a friend gave me his old 8100 pearl a few days ago. i got it unlocked and now i would like to delete all "custom" data and install the newest OS for it to make a fresh start. the question is - when i opt to delete data in the bb desktop software, can i make any horrible mistakes like deleting the imei or someting? i was thinking of just deleting ALL data, is that the way to go?

thanks in advance!

cln