Unable to delete my draft emails with large attachments on Mails app

I have two draft emails that I no longer need. Both have attachments that are apparently too large to save in the drafts folder. I keep getting an error on the messages saying, "This message can't be saved to the Drafts Mailbox. The message contains one or more attachments that are too large to be saved in the Drafts mailbox. Try deleting some attachments." I hit "OK," and then nothing happens. It won't let me delete the draft emails, and the mail icon keeps jumping. Help, please?!

[Re-Titled by Moderator]