The Action Reminder field, for a quote in the Quote List, is a note field where you can add any notes or reminders, this is not visible to Underwriters.
To add a reminder, simply click on the Pen icon in the Action Reminder column for the quote:
Type in your text and press the Green Tick to save.
The Action Reminder dialog will close, and your text will be displayed in the Quotes List for that quote:
To remove or edit the text, then click on the Pen icon and remove the text or edit it accordingly and save.