Yes, you can revert a completed reminder to the pending status.
To revert a reminder to pending status, you can follow either one of the two ways:
1. Click the Reminder icon and select the For me tab. A list of your reminders will be available. Click the completed reminder (strikethrough), and in the pop-up that appears, select Set as Pending.
2. Click the Reminder icon and select the Show Completed icon at the bottom. A list of completed reminders (strikethrough) will appear. Click the green tick button in the reminder. The reminder gets reverted as pending in the For me tab.