I would like to know what's the issue going on for months where I can't run my app on my device because of this issues:
Unable to add device 'iPhone- ' because the team has already reached the maximum number of iPhone devices.
Provisioning profile "iOS Team Provisioning Profile: *" doesn't include the currently selected device "iPhone -".
Code signing is required for product type 'Application' in SDK 'iOS 10.2'
What should I do? the developer web page is different now so I can't edit my account like I've always did : Do I have to pay now to test it on my device?
Mauricio. Here is your big challenge. Apple only gives you ONE opportunity per year to clean your device list; after you renew your membership. So if you have truly reached your max amount of allowed devices you are stuck, even if you disable a device from your list.
When you log into your developer account and go to "Certificates, Identifiers & Profiles" then click "All" under devices you will see a gold tinted bar (as of early 2017) saying you can "reset your device list." It will be very obvious if you are allowed to reset your device list.
Remember you only get one chance per year to clean up that device list. If you can't do this then I'm sorry but you are stuck, you won't be able to follow the other recommended answer because you have reached your device limit.
Here is a related SO question: Delete a device from my developer account to increase the count