I have multiple mailboxes and am not sure if that requires an extra step.
In your inbox there should be a button at the top left to go to either All Mailboxes or the mail account you're in. After you press that there is a group of Inboxes and a group of Accounts. Go into the desired mail account and it will display the folders you sync. Go to Trash, tap the message, then you can use the folder icon to move it to a different folder (Inbox included).