Delete mail from POP3 server

Delete mail from POP3 server

I added another pop3 account to bring its mail into ZOHO.  I want mail to be deleted from the pop3 server when I delete it in Zoho however I can't make this work.

I selected the new pop3 account and set "Delete mails in the server whenever I delete here" but it doesn't delete from the server.

How can I make this work?

Thanks.