Windows 10 Mail will auto-detect the mail server and although it will set the incoming server host name up as instead of the servers will accept either host name. Any device can delete any email and that email will be moved to Trash. You can delete or move an email using either webmail or any connected IMAP client and that will delete or move the email with each IMAP device mirroring that deletion or move for all folders that are synchronised. An email client or email app set up as an IMAP account views your Mailbox in exactly the same way.
The emails are on the Mail server in your Mailbox and seen via an Internet browser.
