Chosen Solution
I have removed email app altogether from my iphone but it still hanging on memory space. see screen shots below I removed all accounts from system and restarted iphone already
Deleting the Mail app only frees up the space that the app was using, not the space that your phone is using to store mail. You need to go into Settings -> Mail -> Accounts and delete the email account(s) that you were using. That should do it.
