In my storage management, it says I have 2.35G of storage in mail, but my mail app has been deleted and I've logged out of my mail on this computer to save space. So somehow it's still holding storage that it won't let me delete. When I got to iCloud.com and click on the mail icon, it says to create a new iCloud address.
MacBook Air
Hello CarrieLiz94 and welcome to Apple Support Communities. It appears you are having some difficulty with leftover email data still consuming space on your Mac.
The root issue here is that deleting the Mail app does not delete the data associated with the app and now that the app has been deleted, options for getting rid of it are somewhat limited.
You can try to manually remove the data. (Note that this is only being suggested because you've already deleted the app and getting it back would involve reinstalling macOS anyway. Were that not to be the case, this is not something you would want to attempt.)
With the Finder active and whilst pressing and holding the Option key on the keyboard, click the Go menu at the top of the screen. As long as you're holding the Option key, you'll see an entry for Library. Choose that. In the Library, you'll see a folder called Mail. This is where the actual data for all those email messages actually resides. Drag it to the trash or the Desktop if the system will not allow you to move it to the trash. Next reboot the Mac and check your storage again
If you decide you do want to use the Mail app again, you'll need to reinstall macOS in order to get it back.
Cheers.
Did you removed the mail account Add or remove email accounts in Mail on Mac - Apple Support
it's not easy to delete the mail app from Mac , as system integrity protection About System Integrity Protection on your Mac - Apple Support will stop the app to delete from the trash .
In user library > the folder mail is never dragged to the trash or desktop .
Not sure what you have done , before reinstalling Mac OS ( erasing the hard drive ) , post some screen shots for pop ups that are appearing , and by the way did you disabled SIP ( using some terminal commands ) .
Can't delete mail storage???
