I sold my Flex Radio to a friend an he needs do open an acoount with his data.

Hi

Yes, he should open his own account for SmartLink.  

Before you sold the radio, did you get a chance to reset the radio?  Or, you can ask your friend to do it by turning off the DC power, pressing down the power button and turning on the DC power while holding down the power button.  It can be released when it turns white.  That is assuming it is a Flex 6400 or 6600 since you don't mention what model it is.

73

This should help

https://helpdesk.flexradio.com/hc/en-us/articles/360020078612-How-to-Completely-Reset-a-FLEX-6000

1.) Unregister the FLEX-6000 from your SmartLink Account

• Start SmartSDR for Windows.  If you are not logged into your SmartLink account, login now.
• Highlight your radio and click on SmartLink Setup
• If you see a green check mark and it indicates your radio is "Configured for SmartLink", click on the blue UNREGISTER button.
• You will get a message that the software is trying to connect to the SmartLink server.  When a connection is made, you will get the message "Hardware Key the radio now".  Press a hardware PTT (foot pedal, mic button, CW paddles). 
• The message "Your radio has been unregistered" will be displayed when you have successfully unregistered your radio from your SmartLink account.

There is no need to delete your SmartLink account even if you do not plan to use it ever again.

2.) Reset The FLEX-6000 Callsign and Nickname

• Connect to the radio using SmartSDR for Windows.  From the top menu bar select the Settings -> Radio Setup -> Radio tab
• In the CALLSIGN field beside the Callsign button, backspace to delete any information in the box and then enter NOCALL.  Press the <ENTER> key when done.
• In the NICKNAME field beside the Nickname button, backspace to delete any information in the box and then enter FLEX-6000.  Press the <ENTER> key when done.
• Close the Radio Setup window.
• Shut down SmartSDR for Windows.

3.) Reset the Internal Database

• Power off the radio

For 6700 and FLEX-6500:

• Press and hold the OK button while pressing and releasing the Power button.
• Release the OK button once the power LED turns white and allow the radio to continue booting normally.

For 6300, FLEX-6400(M) and FLEX-6600(M):

• Press and hold the Power button for approximately 5 seconds until the power button or power LED turn white.
  Release the power button and allow the radio to continue booting normally.