Yes, you can absolutely make your own character movement behavior from scratch, but the question is, does that worth the time and effort?!
Want an empty class? Create a new c++ class based on Character and it will be an empty c++ class. Now, you’re inheriting from both pawn and character.
Want to disable some functionalities? Then don’t use them! it’s as simple as that! Some unused code sitting somewhere in your project will not hurt your game at all!
Do you want to use the walking/running functionalities but thinking of implementing your own jump method? then use the inherited walking/running methods and when it comes to jumping, use your own jump method.
There you go, a modified character class 