How to erase item inside of item in nlohmann::json file C++
basic_json::erase only erases from the currently referenced json node -- so if your json object is the outer object, that would be why you can only erase top-level entries. What you want is a way to get the internal node User1 and call erase on the DeleteMe key from there.
You should be able to easily get a reference to User1 using json_pointer -- which is basically a string-path of the nodes required to traverse to get the node you want. Once you have the node, it should be as simple as calling erase.
Something like this:
auto json = nlohmann::json{/* some json object */};auto path = nlohmann::json_pointer<nlohmann::json>{"/Users/User1"};// Get a reference to the 'user1' json object at the specified pathauto& user1 = json[path];// Erase from the 'user1' node by key nameuser1.erase("DeleteMe");