Delete email in Mail on iCloud.com
Deleted messages are moved to the Bin mailbox. When you delete a message, it is saved in your Bin for 30 days, after which it is permanently erased. When you delete an email from iCloud.com, it is deleted on all your devices that have Mail turned on in iCloud settings.
You can also change where your deleted messages are stored.
Important: If you view iCloud Mail in another app (for example, the Mail app on your iPhone, iPad or iPod touch), your mail might be deleted sooner than 30 days depending on the app’s settings.
Delete messages
In Mail on iCloud.com, select the message or messages you want to delete.
Tip: To select all messages in a folder, press Command-A on a Mac (or Control-A on a Windows computer).
Do either of the following:
If you selected one message: click
at the top right.If you selected multiple messages: click Delete.
If you see 
instead of , you have “Show Archive icon in the toolbar” selected in Mail Settings. See Archive email in Mail on iCloud.com. To delete a message or messages, do one of the following:
If you selected one message: click
at the top right, then click Bin Message.If you selected multiple messages: click Move, click Bin, then click Move.
Empty the Bin
You can delete all the messages in the Bin at the same time.
Important: When you empty the Bin, the messages are permanently deleted. You cannot recover them.
In Mail on iCloud.com, click
at the top of the Mailboxes list.Choose Empty Bin, then click Empty Bin again.
Erase emails immediately and permanently
You can set iCloud Mail to permanently and immediately erase messages when you delete them, instead of moving them to the Bin.
In Mail on iCloud.com, click
at the top of the Mailboxes list, then choose Settings.In the General tab, deselect “Move deleted messages to”, then click Done.
Change the location of deleted messages
By default, messages in iCloud Mail are moved to the Bin when you delete them. You can change the folder they are moved to.
In Mail on iCloud.com, click
at the top of the Mailboxes list, then choose Settings.In the General tab, select “Move deleted messages to”, choose a folder or click
to create a new folder, then click Done.
To delete Mail folders, see Organise email with folders in Mail on iCloud.com.