How to Clean Email.
This time we will take an example for Gmail email.
Delete One Message
- On an Android phone or tablet, open the Gmail app .
- Open the message.
If you want to stay in your inbox, tap the letter or photo next to the message. - Tap Delete .
Delete Multiple Messages
- On an Android phone or tablet, open the Gmail app .
- Tap the letter or photo next to the message you want to delete.
- Tap Delete .
Delete All Messages in a Category
- On your computer, open Gmail.
You cannot delete all messages from the Gmail application. - On the bottom left, click the Down arrow .
- Click All.
If the number of messages is more than one page, you can click Select all conversations. - Click Delete .
Deleting Messages in the Trash
If you don’t want the message to stay in the trash for 30 days, you can delete it permanently.
- On an Android phone or tablet, open the Gmail app .
- On the top left, tap Menu .
- Tap Trash.
- At the top, tap Empty trash now.
Source : https://support.google.com