This method will delete a file on remote server, if
possible. Once completed, the Done event will be
fired. If no error occurs, the ErrorCode argument in the Done event will be set to
0 (zero). If an error occurred, the ErrorCode will hold the number of the error and
ErrorText will contain a description of the error.
No wildcards can be used for the RemotePath argument. The RFC
protocol specification for SFTP does not allow
them.