Xcode – UICollection View not reloading after changing the Array from a button click (button is outside UI Collection view)

I am very new to swift. So TLDR I have a collection view which I want to update after I click a button. I have seen various solutions and everyone suggesting to put collectionView.reloadData but I am not understanding where to put this line in my code. Any help will be appreciated.
This is the view controller:

class myViewController: UIViewController {
    @IBOutlet weak var myCollectionView: UICollectionView!
    
    var charList: Array<String> = []
    
    var data: String = ""
    
    var songTiles = [
        "teri meri": ["D", "A", "G", "A", "F", "G", "A", "F", "G", "A", "G", "F", "E", "D", "E", "D", "C", "D", "E", "F", "E", "F", "E", "G", "A", "G", "F", "E", "D", "D"],
        "faded": ["B", "A", "B", "A"],
        "darmiyan": ["A", "B", "B", "A"],
        "hangover": ["B", "A", "B", "A"],
        "dna": ["A", "A", "A", "A"],
        "fire": ["A", "B", "B", "A"],
        "springday": ["C", "A", "A", "A"],
        "gotcha": ["C", "A", "A", "A"],
        "aurora": ["C", "A", "A", "A"],
        "fadedremix": ["A", "B", "A", "B"]
    ]
    
    @IBOutlet weak var chosenSong: UILabel!


    @IBAction func keyNote(_ sender: UIButton) {
        if (sender.currentTitle == charList[0]) {
            charList.removeFirst()
            print("Correct!")
            playSound(sound: sender.currentTitle!)
        }
    }
    
    func playSound(sound: String) {
        guard let url = Bundle.main.url(forResource: sound, withExtension: "wav") else {
            return

        }
        do {
                    try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default)
                    try AVAudioSession.sharedInstance().setActive(true)
        
                    player = try AVAudioPlayer(contentsOf: url, fileTypeHint: AVFileType.mp3.rawValue)
        
                    guard let player = player else { return }
        
                    player.play()
        
                } catch let error {
                    print(error.localizedDescription)
                }
    }
    
    var player: AVAudioPlayer?
    
    override func viewDidLoad() {
        super.viewDidLoad()
        charList = songTiles[data]!
        chosenSong.text = data

        // Do any additional setup after loading the view.
    }

    
}
 

extension myViewController: UICollectionViewDataSource, UICollectionViewDelegate {
    
   func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return charList.count
    }
    
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        myCollectionView.reloadItems(at: [indexPath])

        let cell = myCollectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! myCollectionViewCell
        cell.myImage.image = UIImage(named: charList[indexPath.row])
        myCollectionView.reloadItems(at: [indexPath])

        
        return cell
    }
    
    
}

So the way this code works is it deletes the character from the start of the array that user has selected each time user presses the button correctly.
For eg if I choose Array Faded and I press A the Array in the UIControllerView should remove A and update collection view accordingly. Think of it as a tutorial of learning songs on xylophone.
Any help would be appreciated. Thanks.