To delete your journal, change the Journal Activation Status to "Deleted" and click on Save Changes. Your journal will be saved for 14 days in case you change your mind, but will not be available during that time.
To undelete your journal before it has been purged, go back to the same place and change your Journal Activation Status to "Activated". Click on Save Changes.
As stated in the InsaneJournal Terms of Service (https://www.insanejournal.com/legal/tos.bml), "Self-committed" [paid] and Permanently Insane accounts are non-transferable and non-refundable. If you have a Self-committed or Permanently Insane account and choose to delete your journal, you will not be able to transfer the remainder of your paid time to another account, nor will you be able to receive a refund for it.