Thanks for posting your situation on Microsoft Q&A,
Based on your description, I understand that you would like to change your Family subscription to Personal subscription, but you are unable to do so.
Firstly, could you please help me check whether you are the owner of your subscription or not? If you are the owner, you can check your account your account status at this Link, and switch your subscription by following these guidelines: Switch between Microsoft 365 subscriptions
Switching to Microsoft 365 Personal and Family Classic Plans
Where can I manage my Microsoft 365 subscription?
In case, you are not, you have to contact to the owner of your Family Subscription and asked them to manage your account.
If the above ways don't work, your best course of action is contact Microsoft Support directly.
Click this link: https://support.microsoft.com/contactus/
Sign in to your Microsoft account. Make sure you log in with your personal account.
Select the product you need help with. Type "Microsoft Office 365" to search and click "Sign in to contact support" at the bottom of the page.
Under Products and Services, select "Microsoft 365 and Office".
Under Categories, select "Manage my Account" and click Confirm.
Click on "Chat with a support agent in your web browser". Follow the prompts to connect with a live agent.
To access the full range of support options, including chat, please contact them during business hours which are Monday to Friday from 9 AM to 5 PM local time.
I hope you can solve the problem smoothly.
Kind regards,