Is that line still under contract? If so, you will owe an Early Termination Fee. The fee is pro-rated, based on the number of months of the contract that have been completed. It also depends on the type of phone that was purchased when the new contract was signed. If you bought a feature phone, the ETF will be $175 less $5/month completed, and if you purchased a smartphone it will be $350 less $10/month completed.
As the account owner, you can see the contract end date for all of your lines in your MyVerizon account. If you have questions, you can always call Verizon and get an exact quote for your ETF.