[Ace 3] There is no 'clear user data' under 'Settings' , how can I erase Ace 3.

[mr.link]

I bought 2 Ace 3 for my two daughters, there was something wrong with  Fitbit APP and the Devices. Child Account couldn't be removed. I couldn't log in Fitbit App either.  
I wanna erase the devices, however I could not find the 'clear user data' function following the instructions as below: https://help.fitbit.com/articles/en_US/Help_article/2216.htm 

[LZeeW]

Hello @mr.link and welcome to the Community.  Very odd, because the Ace 3 manual has the same instructions.  But I have a question and I apologize if I misread what you wrote.  It sounds like you never got the devices set up.  If this is the case, then there is no data to erase.  If I misread what you wrote, can you describe your issue a different way?