Closing an assignment stops students submitting any more work, while leaving everything they have already done in place for you to mark.
Closing it
Open My Library from the sidebar and click your pathway. Set the type filter to Pathways if you have a lot of content.
Click Assign, find the classroom under Already Assigned and click the red Close assignment button on its row.
Mindjoy asks you to confirm before it closes.
A closed assignment shows as Closed, and the same row offers to reopen it.