cookie-session: req.session is null but cookies are not destroyed

I use cookie-session in my Express server that uses Parse Server. Then I have React webapp that do get/post to the server. This is how I setup

app.use(cookieSession({
  name: 'parse-session',
  secret: "SECRET_SIGNING_KEY",
  maxAge: 15724800000
}));

and this is how I save user informations at login:

req.session.user = user;    
req.session.token = user.getSessionToken(); 

it works well because when I call rest api:

 request({
      uri:'http://myapi.com/parse/users/me',
      headers: {
        'X-Parse-Application-Id': 'my-app-id',
        'X-Parse-Session-Token': req.session.token
      },
      json:true    
    
    }).then((userData) => {
       console.log(userData);               
    }).catch((error) => {
        console.log(`User do not exist: ${error}`);
    });

it gives me userData; the problem is at logout because I do this:

if(req.session){
     req.session = null;
       
  }

it put session at null, but if I try to do a request above, using it in React to call Express server:

fetch('/user',{credentials:'include'})
       .then((response)=>{
           return response.json();
       })
       .then((body)=>{
           if(body.user){
               console.log('vv',body.user);
               this.setState({logIn:true});
           }
           else{
               console.log('vv',body);
           }

       }).catch((error)=>{
              console.log('My error:',error);
   
       });

req.session.token continue to exist. Is there a way to delete cookie when put req.session = null ? Because the only way to delete the session token is when I delete history on the browser.