Finding Saved Drafts
Saved drafts can be located in the "Manage PM Drafts" section on the left hand side of your messages page.

From there you can select your drafts and either load it onto a message. Edit it in the Manage PM Drafts section. Or click the box on the right then click the delete messages button to delete the selected drafts.
As for drafts saved from the forum posts. Just go into the new post screen and there should be a button marked Load Drafts, near the Submit button. But that only shows up if you have a saved draft.

From there you can select your drafts and either load it onto a message. Edit it in the Manage PM Drafts section. Or click the box on the right then click the delete messages button to delete the selected drafts.
As for drafts saved from the forum posts. Just go into the new post screen and there should be a button marked Load Drafts, near the Submit button. But that only shows up if you have a saved draft.