using Sitecore;
using Sitecore.Configuration;
using Sitecore.Data;
using Sitecore.Data.Fields;
using Sitecore.Data.Items;
using Sitecore.Layouts;
using Sitecore.SecurityModel;

private bool RemoveRendering(Item targetItem)
        {
            bool isRenderingRemoved = false;
            Database masterDB = Factory.GetDatabase("master");
            Item targetItem = masterDB.GetItem("{2A3E91B0-7987-44C5-AB34-35C2D9DE73B9}");
            string renderingId = "{6S32E1G3-3745-2ED4-09Y6-65T1R5R5YG69}";
            int targetIndex = 2;
            int usecase = 1;
            RenderingDefinition instanceOfRendering = null;

            if (targetItem != null)
            {
                /// Get the layout definitions and the device definition
                LayoutField layoutField = new LayoutField(targetItem.Fields[FieldIDs.LayoutField]);
                LayoutDefinition layoutDefinition = layoutField != null ? LayoutDefinition.Parse(layoutField.Value) : null;
                DeviceDefinition deviceDefinition = layoutDefinition != null ? layoutDefinition.GetDevice(Context.Device.ID.ToString()) : null;
                DeviceDefinition ddef = layoutDefinition.GetDevice(deviceDefinition.ID.ToString());

                /// Get the array of all renderings for the target page item
                IEnumerable<RenderingDefinition> renderingsArray = ddef.Renderings.ToArray().Cast<RenderingDefinition>();

                if (renderingsArray.Count() > 0)
                {
                    switch (usecase)
                    {
                        case 1: /// Remove first instance of rendering

                            instanceOfRendering = GetRenderingDefinition(usecase, renderingId, renderingsArray, targetIndex);

                            if (instanceOfRendering != null && !string.IsNullOrEmpty(instanceOfRendering.UniqueId))
                            {
                                ddef.Renderings = new ArrayList(renderingsArray.Where(r => r.UniqueId != instanceOfRendering.UniqueId).ToList());
                            }

                            break;
                        case 2: /// Remove last instance of rendering

                            instanceOfRendering = GetRenderingDefinition(usecase, renderingId, renderingsArray, targetIndex);

                            if (instanceOfRendering != null && !string.IsNullOrEmpty(instanceOfRendering.UniqueId))
                            {
                                ddef.Renderings = new ArrayList(renderingsArray.Where(r => r.UniqueId != instanceOfRendering.UniqueId).ToList());
                            }

                            break;
                        case 3: /// Remove rendering at specified index
                            instanceOfRendering = GetRenderingDefinition(usecase, renderingId, renderingsArray, targetIndex);

                            if (instanceOfRendering != null && !string.IsNullOrEmpty(instanceOfRendering.UniqueId))
                            {
                                ddef.Renderings = new ArrayList(renderingsArray.Where(r => r.UniqueId != instanceOfRendering.UniqueId).ToList());
                            }

                            break;
                        case 4: ///Remove all instances of rendering
                            ddef.Renderings = new ArrayList(renderingsArray.Where(r => r.ItemID != renderingId).ToList());
                            break;
                    }

                    /// Save the layout changes
                    using (new SecurityDisabler())
                    {
                        targetItem.Editing.BeginEdit();
                        layoutField.Value = layoutDefinition.ToXml();
                        targetItem.Editing.EndEdit();
                    }
                }

                isRenderingRemoved = ddef.Renderings.Count < renderingsArray.Count();
            }

            return isRenderingRemoved;
        }

        /// <summary>
        /// Get the rendering definition of the target rendering from the existing page renderings
        /// </summary>
        /// <param name="usecase"></param>
        /// <param name="renderingId"></param>
        /// <param name="renderingsArray"></param>
        /// <param name="targetIndex"></param>
        /// <returns></returns>
        /// <summary
        private RenderingDefinition GetRenderingDefinition(int usecase, string renderingId, IEnumerable<RenderingDefinition> renderingsArray, int targetIndex)
        {
            RenderingDefinition instanceOfRendering = null;

            switch (usecase)
            {
                case 1: ///get first instance of rendering
                    instanceOfRendering = renderingsArray.Where(x => x.ItemID == renderingId).First();
                    break;
                case 2: ///get last instance of rendering
                    instanceOfRendering = renderingsArray.Where(x => x.ItemID == renderingId).Last();
                    break;
                case 3: ///get rendering definition of rendering at specified index
                    int renderingIndex = MainUtil.GetInt(targetIndex, -1);

                    if (renderingIndex >= 0 && renderingIndex < renderingsArray.Count())
                    {
                        instanceOfRendering = renderingsArray.ElementAt(renderingIndex);

                        if (instanceOfRendering != null && instanceOfRendering.ItemID == renderingId)
                        {
                            ///do nothing
                        }
                        else
                        {
                            instanceOfRendering = null;
                        }
                    }

                    break;
            }

            return instanceOfRendering;
        }