Kotlin MutableLiveData clean or update

Question

I am pulling data from api in my application. I keep the data I have in MutableLiveData. There is no problem so far. However, when I filter and pull other data, it lists the new data under the old data. My goal is to delete the old data and show only the new data.

ViewModel

val breakingNews: MutableLiveData<Resource<NewsResponse>> = MutableLiveData()
    var breakingNewsPage = 1
    var breakingNewsResponse: NewsResponse? = null



     fun getCategoryNews(countryCode: String,category:String) = viewModelScope.launch {
    
    
Is it possible to do a check here?
            breakingNews.postValue(Resource.Loading())
            val response = newsRepository.getBreakingNews(countryCode,category,1)
            breakingNews.postValue(handleBreakingNewsResponse(response))
        }
  private fun handleBreakingNewsResponse(response: Response<NewsResponse>): Resource<NewsResponse> {
        if (response.isSuccessful) {
            response.body()?.let { resultResponse ->
                breakingNewsPage++

                if (breakingNewsResponse == null) {
                    breakingNewsResponse = resultResponse
                } else {
                    val oldArticles = breakingNewsResponse?.articles
                    val newArticles = resultResponse.articles
                    oldArticles?.addAll(newArticles)

                }
                return Resource.Success(breakingNewsResponse ?: resultResponse)
            }
        }
        return Resource.Error(response.message())
    }

Fragment(Observe)

 viewModel.breakingNews.observe(viewLifecycleOwner, Observer { response ->
            when (response) {
                is Resource.Success -> {

                    hideProgressBar()




                    response.data?.let { newsResponse ->
                        newsAdapter.differ.submitList(newsResponse.articles.toList())
                        val totalPages =
                            newsResponse.totalResults / QUERY_PAGE_SIZE + 2 //Sayfada boşluk oluşuyor
                        isLastPage = viewModel.breakingNewsPage == totalPages
                        if (isLastPage) {
                            rvBreakingNews.setPadding(0, 0, 0, 0)
                        }

                    }
                }

Adapter.kt

class NewsAdapter() : RecyclerView.Adapter<NewsAdapter.ArticleViewHolder>() {
    var formatPattern = "yyyy-MM-dd'T'HH:mm:ss"
    inner class ArticleViewHolder(itemView: View): RecyclerView.ViewHolder(itemView)

    private val differCallback = object : DiffUtil.ItemCallback<Article>() {
        override fun areItemsTheSame(oldItem: Article, newItem: Article): Boolean {
            return oldItem.url == newItem.url
        }

        override fun areContentsTheSame(oldItem: Article, newItem: Article): Boolean {
            return oldItem == newItem
        }
    }

    val differ = AsyncListDiffer(this, differCallback)


    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ArticleViewHolder {
        return ArticleViewHolder(
            LayoutInflater.from(parent.context).inflate(
                R.layout.item_article_preview,
                parent,
                false
            )
        )
    }

    override fun getItemCount(): Int {
        return differ.currentList.size

    }


    private var onItemClickListener: ((Article) -> Unit)? = null

    override fun onBindViewHolder(holder: ArticleViewHolder, position: Int) {

        val article = differ.currentList[position]
        holder.itemView.apply {
            Glide.with(this).load(article.urlToImage).into(ivArticleImage)
            tvSource.text = article.source?.name
            tvTitle.text = article.title
            tvDescription.text = article.description

            var formattedTime=setTime(differ.currentList.get(position).publishedAt)

            tvPublishedAt.text = formattedTime

            setOnClickListener {
                onItemClickListener?.let { it(article) }
            }
        }
    }