上传成功后，手动调用上传的删除方法

<el-upload
  ref="mYupload"
  class="upload-demo"
  action="https://jsonplaceholder.typicode.com/posts/"
  :on-preview="handlePreview"
  :on-remove="handleRemove"
  :before-remove="beforeRemove"
  multiple
  :limit="3"
  :on-exceed="handleExceed"
  :file-list="fileList">
  <el-button size="small" type="primary">点击上传</el-button>
</el-upload>
//JS 
methods: {
  clearFiles () {
      this.$refs['mYupload'].clearFiles();
  }
}