To change the type of account go to the control panel at https://developer.apple.com/account
Enter your login and password:
After login, click in the column "Membership" sidebar
You will see the credentials, as well as the button is proposed to amend them. Click on the button danuyu.
In the menu, select the second item, "Change the account type developer":
Next you will be asked to answer a few questions:
Also, choose the right option for your organization in other areas:
After filling out this form, you will receive an email with further instructions and a proposal to pay the membership.