Icloud storage

The Mail app will show your iCloud mail automatically if “Mail” is turned on in Settings, your name, iCloud

Open the Mail app and tap the trash can for each mail you want to delete or tap edit and select all to delete sll

Try going to your iCloud account and see if you can delete it there.

I stand corrected. LD150 knows what he is talking about!

Sometimes.

We could both be right as it isn’t clear why the question arose.