Change code to grab a single file

The current code takes 3 files and puts them into 1 (SEE COMBINE HORIIZONTAL SECTION) and then reads that newly created file and plots it. However, I need to change it so that it only grabs a single file without the combination process. The folder has the files I need to plot already and no combination of files is needed.

% Enter the directory to search
directory = uigetdir('*',"Select Folder With Files To Be Processed");

% List all items in the folder
fileList = dir(directory);

% Delete the subfolders from the list (i.e. only keep files)
fileList(vertcat(fileList.isdir)) = [];
   
app.Lamp.Color = 'Yellow'
  
figure

hold on

% Uses folder as title of plot
[ParentFolderPath] = fullfile(directory);
[~, ParentFolderName] = fileparts(ParentFolderPath);

% Loop through each file, copy it and give new extension: .txt
for i = 1:numel(fileList)
    file = fullfile(directory, fileList(i).name);
    [tempDir, tempFile] = fileparts(file);
    status = copyfile(file, fullfile(tempDir, [tempFile, '.txt']));
end

% Combine HORIZONTAL text files

if app.HorizontalButton.Value == 1;

    fileName = ParentFolderName + " HORZ NOM.txt";
    
    dL = dir(fullfile(directory,'*HLF*NOM.txt'));
    dM = dir(fullfile(directory,'*HMF*NOM.txt'));
    dH = dir(fullfile(directory,'*HHF*NOM.txt'));
    
    for i = 1:numel(inf)
    
      HORZtD = readtable(fullfile(dL(i).folder,dL(i).name),'numheaderlines',6,'readvariablenames',1);
      HORZtD = [HORZtD;readtable(fullfile(dM(i).folder,dM(i).name),'numheaderlines',6,'readvariablenames',1)];
      HORZtD = [HORZtD;readtable(fullfile(dH(i).folder,dH(i).name),'numheaderlines',6,'readvariablenames',1)];
      
      writetable(HORZtD,fullfile(directory, fileName));

      % Adding the line to the plot with options for color and marker
      if app.HorizontalMarkersButton.Value == 1;
        Hplot = plot(HORZtD.Frequency,HORZtD.SE,"Color",app.HorizontalColorDropDown.Value,'LineWidth',str2num(app.LineWidthDropDown.Value), ...
            Marker=app.HorizontalMarkerDropDown.Value,DisplayName='Horizontal');
      else
        Hplot = plot(HORZtD.Frequency,HORZtD.SE,"Color",app.HorizontalColorDropDown.Value,'LineWidth',str2num(app.LineWidthDropDown.Value), ...
            DisplayName='Horizontal');
      
      hold on

      end
    end
end