Method unload

packages/designer/src/project/project.ts:246–253

* 卸载当前项目数据

()

   * 卸载当前项目数据
   */
  unload() {
    if (this.documents.length < 1) {
      return;
    }
    for (let i = this.documents.length - 1; i >= 0; i--) {
      this.documents[i].remove();
    }
  }

  removeDocument(doc: IDocumentModel) {
    const index = this.documents.indexOf(doc);