//файл с дизайнером, в котором только ввод числа текстбоксов и кнопка

namespace WinFormsApp2
{

    partial class Form1
    {
        /// <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.button1 = new System.Windows.Forms.Button();
            this.textBoxCreateInput = new System.Windows.Forms.NumericUpDown();
            ((System.ComponentModel.ISupportInitialize)(this.textBoxCreateInput)).BeginInit();
            this.SuspendLayout();
            // 
            // button1
            // 
            this.button1.Location = new System.Drawing.Point(138, 12);
            this.button1.Name = "button1";
            this.button1.Size = new System.Drawing.Size(75, 23);
            this.button1.TabIndex = 1;
            this.button1.Text = "Create";
            this.button1.UseVisualStyleBackColor = true;
            this.button1.Click += new System.EventHandler(this.button1_Click);
            // 
            // textBoxCreateInput
            // 
            this.textBoxCreateInput.Location = new System.Drawing.Point(12, 12);
            this.textBoxCreateInput.Maximum = new decimal(new int[] {
            10,
            0,
            0,
            0});
            this.textBoxCreateInput.Name = "textBoxCreateInput";
            this.textBoxCreateInput.Size = new System.Drawing.Size(120, 23);
            this.textBoxCreateInput.TabIndex = 2;
            // 
            // Form1
            // 
            this.AutoScaleDimensions = new System.Drawing.SizeF(7F, 15F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(800, 450);
            this.Controls.Add(this.textBoxCreateInput);
            this.Controls.Add(this.button1);
            this.Name = "Form1";
            this.Text = "Form1";
            ((System.ComponentModel.ISupportInitialize)(this.textBoxCreateInput)).EndInit();
            this.ResumeLayout(false);

        }

        #endregion
        private System.Windows.Forms.Button button1;
        private System.Windows.Forms.NumericUpDown textBoxCreateInput;
    }
}

//------------------------------------------------------------------------------

//файл с "логикой", где эта вот залупа происходит
namespace WinFormsApp2
{
    using System;
    using System.Collections.Generic;
    using System.Drawing;
    using System.Windows.Forms;

    public partial class Form1 : Form
    {
        List<TextBox> _txtBox = new();
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            foreach(var x in _txtBox)
            {
                Controls.Remove(x);
                x.Dispose();
            }
            _txtBox.Clear();

            int posX = 12;
            int posY = 35;
            int marg = 25;
            for(int i = 0; i < this.textBoxCreateInput.Value; i++)
            {
                _txtBox.Add(new TextBox
                {
                    Text = $"{i+1}",
                    Name = $"textBox{i}",
                    Location = new Point(posX, posY),
                    Size = new Size(100, 23),
                });
                posY += marg;
                Controls.Add(_txtBox[i]);
            }
        }
    }
}