NotePlanN
NotePlan

Remove the schedule tag when adding a done tag

So something like a remove scheduled due date upon completion, or a update scheduled due date up completion. Which I think would be effectively the same thing. Otherwise, you have a reference of the task for the due date and for the completion date if they differ.
CompletedCompleted

Implemented in the latest beta and soon available in the App Store

This could be generalized: In preferences, for each task state (open, completed, canceled, rescheduled), a list of tags that are canceled when that state ceases to apply. So if you have an `#urgent` tag, you could list it with the `Open` status, and when you check off an urgent task, the tag is removed automatically.