how to delete whole flatlist in one go and whole firestore collection

deleting whole flatlist in one go using firestore 

filter data=(_item)=>{

   this.setState({users: this.state.users.filter(item => item. Key=== _item)});

    console.log(this.state.favorites) }

call this function in button deleteall code given below

  {   async function massDeleteUsers() {

              // Get all users

              const usersQuerySnapshot = await firestore().collection(‘user’).get(

              );

              // Create a new batch instance

              const batch = firestore().batch();

              usersQuerySnapshot.forEach(documentSnapshot => {

                batch.delete(documentSnapshot.ref); });

              return batch.commit();}

           massDeleteUsers().then(() =>{

             this.filterdata()

               console.log(‘All users deleted in a single batch operation.’)}) }}>

so this will delete whole flatlist in on go and delete whole firestore collection