When I delete my email on my iPhone & iPad it is deleting it on my Mac desktop. How can I stop this from happening? I use I Roadrunner email with Time Warner.
If I get you right then Ben & HA14 are getting it exactly wrong... You're saying that changes you're making on your iPhone & iPad are reflected on the Mac. This is because you're using IMAP.
The purpose of IMAP is to keep all computers/devices synched with the server, so this is the expected behaviour. Delete a message in one place and it will be deleted from the other devices; send a message from one and the copy in "Sent" will appear in the other devices etc. If you're not happy with that (but why would you want your devices to have different subsets of your email?) then you can switch to POP and set it to "delete message from server after download". That way, every message downloaded will ONLY exist on that device, and deleting it will have no impact elsewhere.
maybe roadruner is using pop3 protocol and not IMAP protocol
You're probably using POP3 for email instead of IMAP. We've discussed the differences here:
Read about them to understand; POP and IMAP differ in their handling of local copies and deletion.
How-To Geek has elaborated on this recently:
Do note, though, that deleting emails is universal. If you delete an email from your account, it doesn't matter where you deleted it. Deleting from your phone removes it from your account and therefore you won't see it on your desktop.