Here's the long trek to get there:
- Go to iCloud.com.
- Log in with your Apple ID.
- Click the big Mail icon.
- Click the gear icon at the top right of the window, then choose Preferences...
- Choose the Accounts view.
Instead of deleting an alias, you can temporarily turn it off by unchecking "Read mail and send mail from this alias." Aliases that are not active or have been deleted will not receive messages and the messages will bounce back to the sender.
Here are a couple of other things you can do with iCloud aliases:
- Assign a color to an account. This is really only useful when you are looking at your email from iCloud.com. The assigned colors do not show up in Mail for the Mac or iOS devices.
- Change the alias Description. The description is only seen by you and is for your information only.
- Change the Full Name. The full name is the name that your email recipients see as the FROM name on your emails.