C# firebird嵌入式断开连接无法删除文件

FbConnectionStringBuilder connStrBd = new FbConnectionStringBuilder();
    connStrBd.Charset = "UTF8";
    connStrBd.UserID = "SYSDBA";
    connStrBd.Password = "masterkey";
    connStrBd.ServerType = FbServerType.Embedded; // 设置数据库类型为嵌入式
    connStrBd.Dialect = 3;
    string FDBConn = "";
    connStrBd.Database = filePathName;
    FDBConn = connStrBd.ToString();
    FbConnection connFrom = new FbConnection(FDBConn);
    connFrom.Open();
    connFrom.Close();
    FbConnection.ClearPool(connFrom);
FbConnection.ClearPool(connFrom); 可以关闭该文件的所有连接