The Pro settings were hidden by default since Caldera Forms 1.8.9. They are still showing if an active connection to the Pro app is detected. In case a user needs to activate a new connection, that can be done using the ‘caldera_forms_show_pro_ui’ filter hook.
How To Restore The Caldera Forms Pro Menu
You can use this plugin and activate it after using the Upload plugin button in the Add plugin page.
You will find the code at https://gist.github.com/New0/1bb86a633b573c31e922c1b399fce656 which can also be used as a WordPress plugin or just copied and pasted isolating the filter hook line 8 in a functions.php file of a (child-)theme.
Where Does This Code Go?
When using WordPress hooks to customize Caldera Forms or other plugins you should not modify the plugin files, or you will lose your changes when you update the plugin. Instead you should create a small plugin to hold the custom code. It's easy, learn how here.
Technically you can add the custom code to your theme's functions.php, but then you will not be able to change your theme and keep these customizations.