There are following two possible ways to validate if a key exists in the object or not.

let object = {"name":obama,"age":98}
// Using in operator
if('name' in object){
// some code 
}

// Using hasOwnProperty() method
if(object.hasOwnProperty('Fname')){
// some code
}

remove key from object JavaScript

let object = {"name":obama,"age":98}
delete object.name;

Add key in an JavaScript object 

let object = {"name":obama,"age":98}
delete object.Fname = "david";