I want to make sure that the web host provider doesn't have access to my web mail how can i assure such a thing? i set the outlook setting to remove any emails from the server.
when i click on the email disk usage i can see that my email address has 0 emails in inbox but the default account has 154 emails in the inbox, i can't access the default email, can the web host provider access default account emails ? and in this case he can access all my emails ?
When you say you cannot access the Default email account, what do you mean by that exactly?
In your cPanel > Email section > Email Accounts, do you have the "Default Email Account" tab displayed on top of that page? I'm assuming you do, is there an account listed there? If yes, is there a link to Access Webmail? If yes, what error, if any, do you see when you click it?
Your Hosting Provider, as the root user, can access anything on the server. If you're using IMAP and leaving a copy of the email on the server, your Host could, if they wanted to, see that email. If you download all email, the chances of them seeing your email is less, but still possible as the mail travels thru the server.
If the Default Email Account has 154 emails in it taking up space, you should generally be able to access it and remove them. Most likely worthless bounces of some sort. If you can't, your Hosting Provider can surely remove them for you, or at least, answer why you're unable to access them yourself.
Ask them and let us know how it goes. I'm not sure why they'd be blocking access to this default account.