Backup to FTP

[MINISTAR]

When I am testing online backup (FTP) I get this log:
Connecting to ftp.XXXXXXXX.com:21...

Connected to the remote server.
Logging in...

Logged in into the remote server.
Changing the initial directory to "/"...
The remote directory was successfully changed to "/"

Creating a test file to upload...
Uploading the test file...

The test file was successfully uploaded. Login in to your server manually to analyze and delete the file.

The client is now disconnected.
Deleting the test file from the temporary directory...

I can see file on FTP site but file can not be deleted
Also when I run task, files I removed from my PC are still on FTP site. Mirror option should delete those files?
Any advice

PS
How I use SFTP protocol?

[cobian]

The file is not deleted automatically. It is there in order to see if the connection works.

[cobian]

Mirror works only with local files, never with remote backups.

[MINISTAR]

That make sense.
Thanks!