if the account in question is Pay As You Go then there is no problem.
You just need to contact customer services (free on 789 from a Virgin mobile) 0345 6000 789 from any other phone. Confirm three characters from your account password and tell them which account you wish to unregister. If your daughter is with you she can then create her own account in the same call.
If the account in question is Pay Monthly then it's not possible to transfer the contract into another person's name.
This is because you will have been credit checked and are legally responsible for the account. (Although I believe that you could change the bank funding details).
If it is 30 day rolling SIM only plan, you can give notice. At the end of which it will become PAYG and can then transferred into your daughters name.
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I'm thinking of doing the same thing. My son is 19 and I think is now ready to pay his own mobile bill! It does seem a palaver though for me to have to end a contract and he then start a new one. Also, he is currently on a 'double data' 30-day rolling contract deal which he would lose if I ended the contract and he started a new one. Looks like he is in luck and I'll continue to pay his bill!