TIMResult res = TencentIMSDK.MsgClearHistoryMessage(conv_id, TIMConvType.kTIMConv_C2C, (int code, string desc, string user_data) => {
  // 处理回调逻辑
 });

 TIMResult res = TencentIMSDK.MsgClearHistoryMessage(conv_id, TIMConvType.kTIMConv_Group, (int code, string desc, string user_data) => {
  // 处理回调逻辑
 });