Delete all files and folders in a certain FTP source folder

I am having trouble accessing my FTP folder on my online server. 
I do not think DirectoryInfo and FileInfo were ment for an FTP source folder.
I just want to delete all files and folders in a certain FTP source folder.
This is an excerpt from a working ftp delete file except for the "ftpsourcefolder" which is unknown:
private string host = "ftp://mysite.com"; private string user = "ftp12345"; private string pass = "password"; private FtpWebRequest ftpRequest = null; private FtpWebResponse ftpResponse = null; private Stream ftpStream = null; private int bufferSize = 2048;
DirectoryInfo di = new ...