Not sure if this is how you do it, but in the "Detalles de la membresía" section, there should be a blue link that says (in English) "Update your information". It has a little + sign in a circle.
When you click that a dialog box should appear with an option to convert to an individual account.
If that option is there, click it and follow any on-screen instructions.
If it's not there, then you may have to get in touch with Apple Developer Support via this page: https://developer.apple.com/contact/ and ask that your account be changed to an individual account.
That's all I can do to help you, sorry. I've never had to do this myself.
Topic:
Developer Tools & Services
SubTopic:
Apple Developer Program