How to Delete Email Messages on HP and Laptop or Computer is the same.
This time we will take an example for Gmail email.

Delete One Message

1. On an Android phone or tablet, open the Gmail app .
2. Open the message.
   If you want to stay in your inbox, tap the letter or photo next to the message.
3. Tap Delete .

Delete Multiple Messages

1. On an Android phone or tablet, open the Gmail app .
2. Tap the letter or photo next to the message you want to delete.
3. Tap Delete .

Delete All Messages in a Category

1. On your computer, open Gmail.
   You cannot delete all messages from the Gmail application.
2. On the bottom left, click the Down arrow .
3. Click All.
   If the number of messages is more than one page, you can click Select all conversations.
4. 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.

1. On an Android phone or tablet, open the Gmail app .
2. On the top left, tap Menu .
3. Tap Trash.
4. At the top, tap Empty trash now.

Source : https://support.google.com