Check your account details and make sure you are the account holder or an authorized user
Pay off any remaining device balances, installment plans, or past-due charges
Back up any data on the line you want to cancel
Contact T-Mobile customer care by phone, chat, or in a T-Mobile store
Request cancellation of the specific line
Provide account verification information when asked
Confirm the effective cancellation date
Ask for a final bill and any prorated charges or credits
Return any leased or required equipment if applicable
Save the confirmation number or cancellation receipt
Review your next bill to verify the line was removed