do a search for change of ownership in the search bar... it should be this link
http://support.sprint.com/support/article/Customer_Instructions_for_Change_of_Ownership/2a4c5654-b645-4613-8262-a689a275e885?question_box=change of ownership&id16=change of ownership
make sure both parties fill out whatever
if it's YOUR account and you want to create a seperate account under YOUR name that will be a problem
but if you want to simply move one phone from a share plan or something and make it it's own plan you can have a CSR do that in minutes.
Thanks for your post. I understand you are inquiring if you have to be 18 or older to have a Sprint account under your name and the answer is "Yes". This is a requirement for Sprint post-paid service and a credit evaluation is required to establish service.
Sprint Social Care Team