You are welcome to disable our framework CSS and/or skin CSS if you wish, but you would obviously need to write your own CSS to handle columns, effects etc. This can be done under global settings.
Check the ‘Advanced’ tab.
Note that some of our CSS may be required, despite you applying additional styles in Elementor.
We also have various optimization methods you can use to reduce CSS sizes. Personally I recommend enabling the ‘Compile CSS’ and ‘Inline CSS’ options. I also recommend ensuring you have SCRIPT_DEBUG set to false to ensure WS Form uses minimized files wherever possible.