To complete a transfer of responsibility and transfer your phone number, plan and agreement (if applicable) you will have to contact us through one of our customer service channels, which you can find here.
Your friend will need to contact us after you've given your authorization to transfer the number.
Here are the additional points to mention:
When your friend takes ownership of your line, we will have to do a credit evaluation to activate your friend's new monthly service.
Hope this answers your questions!