How to remove string stored in sharedPrefererences?

Good,  I encounter the problem of having a favorite list and need to remove it by clicking the favorite times item that is saved in the shared preferences.

I have a list that is my favlist which contains json like this:

{"0":"1016","horarioId":"1016","1":"5","horarioLinhaId":"5","2":"36","horarioParagemId":"36","3":"07:24:00","horarioHora":"07:24:00","4":"Activo","horarioEstado":"Activo","5":"5","linhaId":"5","6":"Amarela 6","linhaNome":"Amarela 6","7":"Activa","linhaEstado":"Activa","8":"36","paragemId":"36","9":"Av. da Liberdade \/ Esc. Guilherme Stephens","paragemRua":"Av. da Liberdade \/ Esc. Guilherme Stephens","10":"39.743624","paragemLatitude":"39.743624","11":"-8.930787","paragemLongitude":"-8.930787","12":"Activa","paragemEstado":"Activa"}

Now the problem comes up that I need to remove an item from those favorites stored in sharedpreferences in the form of a string

and what I get is {horarioHora:10:33:00 , horarioEstado:Activo} through the adapter

 public void to_List() {

        List<HashMap<String, String>> favorites =  MyUtility.getFavList(HorariosActivity2.this);
        if(favorites != null){
            ListAdapter adapter = new SimpleAdapter(this, favorites, R.layout.list_item,
                    new String[] {TAG_TITLE, TAG_DATESTART},
                    new int[] {R.id.title, R.id.estado});
            listaHorarios.setAdapter(adapter);

        }
        else {
            Toast.makeText(HorariosActivity2.this, "erro", Toast.LENGTH_SHORT).show();

        }

What I do to get the values is:

String horarioitem = listaHorarios.getAdapter().getItem(position).toString();

My utility where I have the putString getString functions and where do I create my list getfavList emoveFavorite to remove favorites that is not giving addFavorite to add the favorites it is giving:

private static final String EVENTOS = "Fav_eventos";
private static final String TAG_TITLE = "horarioHora";
private static final String TAG_DATESTART = "horarioEstado";

public static boolean addFavorite (Activity activity, String favItem) {
    //get previous favorite items
    String favList = getStringFromPreferences(activity, null, EVENTOS);
    //append new favorite items
    if(favList != null){

        if(favList.equals("")){
            favList = null;
            favList = favItem;
        } else {
            favList = favList + ", " + favItem;
        }
    } else {

        favList = favItem;
    }
    //save in sharedpreferences
    return putStringInPreferences(activity, favList, EVENTOS);
}

public static boolean removeFavorite (Activity activity, String favItem) {
    //get previous favorite items
    String favList = getStringFromPreferences(activity, null, EVENTOS);
    //append new favorite items
    if(favList != null){


        if(favList.contains(favItem) == true){
            favList = favList.replace(favItem, "");
        }
        while (favList.contains(", , ") || favList.contains(", ")){
            favList = favList.replace(", , ", "");
            favList = favList.replace(", ","");
        }
    }
    //save in sharedpreferences
    return putStringInPreferences(activity, favList, EVENTOS);
}

public static boolean isSave (Activity activity, String favItem) {
    //get previous favorite items
    String favList = getStringFromPreferences(activity, null, EVENTOS);
    //append new favorite items
    if(favList != null) {

        if (favList.contains(favItem) == true) {
            return true;
        } else {
            return false;
        }
    }
    return false;
}

public static List<HashMap<String, String>> getFavList (Activity activity){

    String favList = getStringFromPreferences(activity, null, EVENTOS);
    ArrayList<HashMap<String, String>> eventoList = new ArrayList<>();
    if(favList != null){


        favList = favList.replace("\":", "\"=");
        String[] array = favList.split(",\s");
        try{
            for(int i=0; i < array.length; i++){
                JSONObject cursor = new JSONObject(array[i]);
                String title = cursor.getString(TAG_TITLE);
                String datestart = cursor.getString(TAG_DATESTART);

                HashMap<String, String> evento = new HashMap<>();
                evento.put(TAG_TITLE, title);
                evento.put(TAG_DATESTART, datestart);
                eventoList.add(evento);
            }//end for
        } catch (JSONException e){
            e.printStackTrace();
        }//end try

        return eventoList;
    } else {

        return null;
    }// end if

}

private static boolean putStringInPreferences(Activity activity, String nick, String key){
    android.content.SharedPreferences shared = activity.getSharedPreferences("horarios",Activity.MODE_PRIVATE);
    android.content.SharedPreferences.Editor editor = shared.edit();
    editor.putString(key, nick);
    editor.commit();
    return true;
}

private static String getStringFromPreferences (Activity activity, String defaultV, String key) {
    android.content.SharedPreferences shared = activity.getSharedPreferences("horarios",Activity.MODE_PRIVATE);
    return shared.getString(key, defaultV);
}

The final goal is to click remove the schedule from the favorites.