how do i register a new blackberry ID on my 9850

my mom has a 9850. she went out of country, left it behind. i wanted to try it out. backed up her data, then restored my current phone's (9900) data onto it, so it could be mine for a while. i used it, it was cool, blah blah, personally love my 9900. but yeah, my blackberry ID seems to still be registered onto the 9850, how do i log it back into my mom's blackberry ID?

yyyyou'rrre innn troooubllle,,, go to your room,,, you're grounded w/ no BBs for a week...:crying:

i got it newbs all it took was a wipe :)