I included the "form" code inside the main code block so it reads odd and there's lots of extra lines but I didn't have to build a DLL file this way...
 

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using ScriptPortal.Vegas;

namespace Remove_Selected_Effects
{
    public partial class frmRSE : Form
    {
        public Vegas myVegas;

        public frmRSE(Vegas vegas)
        {
            myVegas = vegas;
            InitializeComponent();

            foreach (Track myTrack in myVegas.Project.Tracks)
            {
                if (myTrack.IsVideo())
                {
                    foreach (TrackEvent evnt in myTrack.Events)
                    {
                        if (evnt.Selected)
                        {
                            VideoEvent vEvent = (VideoEvent)evnt;
                            foreach (Effect eff in vEvent.Effects)
                            {
                                string effName = eff.Description;
                                if (!cklEffects.Items.Contains(effName))
                                {
                                    cklEffects.Items.Add(effName, false);
                                }
                            }
                        }
                    }
                }
            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            foreach (Track myTrack in myVegas.Project.Tracks)
            {
                if (myTrack.IsVideo())
                {
                    foreach (TrackEvent evnt in myTrack.Events)
                    {
                        if (evnt.Selected)
                        {
                            VideoEvent vEvent = (VideoEvent)evnt;
                            foreach (object itemChecked in cklEffects.CheckedItems)
                            {
                                string effName = itemChecked.ToString();
                                foreach(Effect eff in vEvent.Effects)
                                {
                                    if (effName == eff.Description)
                                    {
                                        vEvent.Effects.Remove(eff);
                                    }
                                }
                            }
                        }
                    }
                }
            }

            this.Close();
        }

        /// <summary>
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.IContainer components = null;

        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Windows Form Designer generated code

        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            this.label1 = new System.Windows.Forms.Label();
            this.button1 = new System.Windows.Forms.Button();
            this.cklEffects = new System.Windows.Forms.CheckedListBox();
            this.SuspendLayout();
            //
            // label1
            //
            this.label1.AutoSize = true;
            this.label1.Location = new System.Drawing.Point(11, 24);
            this.label1.Margin = new System.Windows.Forms.Padding(2, 0, 2, 0);
            this.label1.Name = "label1";
            this.label1.Size = new System.Drawing.Size(128, 13);
            this.label1.TabIndex = 1;
            this.label1.Text = "Select Effects to Remove";
            //
            // button1
            //
            this.button1.Location = new System.Drawing.Point(110, 262);
            this.button1.Margin = new System.Windows.Forms.Padding(2);
            this.button1.Name = "button1";
            this.button1.Size = new System.Drawing.Size(151, 31);
            this.button1.TabIndex = 2;
            this.button1.Text = "Remove Effects";
            this.button1.UseVisualStyleBackColor = true;
            this.button1.Click += new System.EventHandler(this.button1_Click);
            //
            // cklEffects
            //
            this.cklEffects.CheckOnClick = true;
            this.cklEffects.FormattingEnabled = true;
            this.cklEffects.Location = new System.Drawing.Point(14, 40);
            this.cklEffects.Name = "cklEffects";
            this.cklEffects.Size = new System.Drawing.Size(382, 214);
            this.cklEffects.TabIndex = 5;
            //
            // frmRSE
            //
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(408, 304);
            this.Controls.Add(this.cklEffects);
            this.Controls.Add(this.button1);
            this.Controls.Add(this.label1);
            this.Margin = new System.Windows.Forms.Padding(2);
            this.Name = "frmRSE";
            this.Text = "Remove Selected Effects";
            this.ResumeLayout(false);
            this.PerformLayout();

        }

        #endregion
        private System.Windows.Forms.Label label1;
        private System.Windows.Forms.Button button1;
        private System.Windows.Forms.CheckedListBox cklEffects;
    }
}

public class EntryPoint
{
    private static Remove_Selected_Effects.frmRSE form;

    public void FromVegas(Vegas vegas)
    {
        form = new Remove_Selected_Effects.frmRSE(vegas);
        form.ShowDialog();
    }
}