You need to contact o2 direct on 0344 809 0202 and return it under the 14days return policy, and also contact the police and report your daughter for fraud, as she has fraudulently used your details to obtain goods by deception.
Also note o2 may take action as well against your daughter.
You don't need to give O2 a reason for your change of mind so best not to make a fuss and land your daughter with a criminal record!
I'm sure you can deal with her yourself..... after changing your password
Change of mind details here https://www.o2.co.uk/help/device-and-sim-support/returning-your-device