ASked this question years ago. Does anyone know where I can find this info or know themselves?
what is the question?
How to save the current level?
Not using a level unlocking system through the UI.
In the Title
Are you talking about Save Game? If so here: UE4 - Tutorial - Save and Load - YouTube
To save the whole level tough you should create a struct for each character and item then add them to another struct and save it. On load go through the main struct and spawn each character and item into the world, at least that how I do it.
Thank you very much for responding. What do you mean by creating a struct for each character?
Its just a simple game 1 character but multiple levels. Just want it to load when you click play your current level. 
Good now, all you need to do is add character location, and when you have more complex levels you can add structs like these so all of your data is easy to access. That way you add struct on a struct until you have all of your data in one struct. Again there are few other ways to do it but this one is without getting into code and not to complex. Good luck.
Made Variable (Name) In save Game