How to delete all mail on iphone cydia

I think there may be a bit of confusion here!

Cydia is a third-party app store for jailbroken iOS devices, which allows users to install tweaks and modifications that aren't available through the official App Store. However, deleting all mail on an iPhone is a standard feature that can be done through the built-in Mail app, and doesn't require Cydia or jailbreaking.

To delete all mail on an iPhone, follow these steps:

1. Open the Mail app on your iPhone.
2. Tap on the "Mailboxes" tab at the bottom of the screen.
3. Tap on the mailbox you want to delete all mail from (e.g., "Inbox", "Sent", "Trash", etc.).
4. Tap on the "Edit" button in the top-right corner of the screen.
5. Tap on the "Select All" button at the top of the screen.
6. Tap on the "Delete" button at the top of the screen.
7. Confirm that you want to delete all selected messages by tapping "Delete" again.

Alternatively, you can also delete all mail on an iPhone using the "Mail" settings:

1. Go to Settings > Mail, Contacts, Calendars.
2. Tap on the account you want to delete all mail from.
3. Tap on "Mail Days to Sync" and set it to "1 day" or "All".
4. Tap on "Delete" to delete all mail from the account.

Please note that deleting all mail on an iPhone will permanently remove all messages from your mailbox. Make sure you have backed up your important emails before doing so!