Were you ever Alltel customers? Do you still have an Alltel plan??? If her phone is an Alltel phone the ETF is $200 based on the Alltel terms of Service. Once she gets a new one at the appropriate time, the new device would fall under Verizon's Terms of Service.
There are several options for you to do. Instead of canceling her phone have you talked to her about taking Assumption of Liability for the phone. In other words For her to split off of your plan on to a single plan all on her own to where she would be the Account owner all on her own given she is at least 18 years of age (19 in Alabama). Is there anyone else in the family or do you know of anyone else that needs a phone for them to take What we call AOL (Assumption of Liability.) for the phone? If not the I would say just wait out those last few months with the phone turned off until it comes out of contract into a month to month thing. Then Disconnect. Who knows you might find someone during that time to take over the phone from you. This way you can avoid any ETF fees. If not I say call and they would be happy to discuss anything you need provided you are the account owner or account manager.