[Users] how to delete messages on server with IMAP?

[testing at x84.org]

Hello,

I figured out that the folders in my mailbox on the server do not
replicate locally in the claws client unless I use IMAP.  So this is nice
because it means I have my folders copied to my local claws client.

but what I want to do is I want to keep all my mail in my local claws
client, I want to delete it from the server.  How can I tell Claws to do
this?  It does not let me change the protocol of the account settings from
IMAP to POP3.

Thanks,
-Elliot