Tap on the "Folders" button in the left side panel. Then tap on the folder icon button beside an email account to show the folders. You may have to tap the left arrow beside the folder heading to go back to the correct account.
Then tap on the folder settings button (cog) above the folder list to edit the email folders.

In the top of the folders list screen, tap on the action menu (circle with 3 dots button) to create a new folder.

To rename the folder, tap to the select a folder checkbox and choose 'Rename' from the action menu.

Use the menu action 'Folder Settings' to edit folder settings. You can change the number or age of new emails that are loaded. You can also turn on the setting to automatically delete old emails. View

When you select a folder checkbox, you can use the delete button at the top to remove the folder.

Use the circle icon to refresh the email folder list. Always check inside the Inbox to see if you have folders located there.