how can I change my accout from a childrens account and i no longer have access to the...

This really depends on the initial birth year selected when you created the account
If you didn’t changed that, you can check it here
https://account.microsoft.com/profile

Can you tell me when its supposed to?

Hi and thanks for reaching Microsoft Xbox gamer's community. My name is Josef.
I'm an Independent Advisor and a Microsoft Xbox user like you.

Hope you're doing great today despite this Vrocoso

Sorry to say but in this case you may need to wait until your Microsoft account reach the adulthood if the family organizer account can’t be accessible

Check if your account is an adult access this can stop you from changing it if it's seen as a children's account

I have an X Box One with gold pass and want to add my children as users with their own gamertag is this possible from my account? Thanks.

As long as your xbox account is set to the console any xbox accout create and used on that xbox will have access to the gold memebership.

Just set them up there own xbox account and whatever gamertag you want them to have. Just set up child protection and locks.