ftp multiple delete - mdelete
You can delete multiple files using the mdelete (mdel) command.
You will probably be in interactive mode so you'll have to answer y to each entry. You can disable this by entering <i>prompt</i> to turn off interactive mode.
I think that the mdel command is an extension of the original ftp protocol so it may not work with all servers.
It can delete subdirectories and files as well, so be careful, especially if you use non-interactive mode!