Remove unused code

src/Avalonia.Controls.ColorPicker/ColorPicker/ColorPicker.cs

@@ -1,10 +1,4 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-
-namespace Avalonia.Controls
+namespace Avalonia.Controls
 {
     /// <summary>
     /// Presents a color for user editing using a spectrum, palette and component sliders within a drop down.

src/Avalonia.Controls.ColorPicker/ColorView/ColorView.cs

@@ -28,7 +28,6 @@ namespace Avalonia.Controls
         private TextBox?    _hexTextBox;
         private TabControl? _tabControl;
 
-        private ObservableCollection<Color> _paletteColors = new ObservableCollection<Color>();
         private ColorToHexConverter colorToHexConverter = new ColorToHexConverter();
         protected bool ignorePropertyChanged = false;