email deleted on email client is still in the inbox on my iphone
POP mail servers do not synchronise their data between devices in the way IMAP does. 

Each device will download any mail in the queue when asked &amp; will not auto-delete anything, except for any set server timeout interval, which is adjustable from Mail on the Mac or from iDevice - Settings > Mail, Contacts… > [the email account] Advanced > Delete from Server…

Other than that, deletion once downloaded is manual, per device.