My email account was recently compromised so I created a new address and deleted the old one from my PC and android. How do I ensure the old email address and the ols emails are deleted from the server?
When you are sure the address and your whole network are secure, you can consider what to do for the future. Start by choosing a new email address that is not linked to an ISP, and offers security to match what you are using it for - (VM does not offer 2FA or any tracing of who is accessing your address, although they do block accounts that have suspicious activity). When you have migrated all your contacts and connections away from the address you don't want, then use webmail to delete the contents of all the folders and address books. This will reduce the data available if it should be broken into again.
Is the address linked to your current VM billing account? Is it the primary address - you can't delete it - just stop using the mailbox and let it go dormant after 150 days of non-use. It still remains as the username on the account. If it is a secondary address go to the manage accounts tab and deletion options are there. Use the service of https://mailtester.com to confirm the mailbox has been deleted from the servers.