Set reminder status to "open / done"

When you have finished with a reminder you can close it by setting its status to "done". Put a checkmark against the reminder and select the "Set done status" command at the foot of the table. Click "Execute" to change the reminder's status. Now a blue checkmark is put to the right of the name of the reminder, and a message appears in green above the table to say that the status/es has/have successfully been changed.

You can reset the status of reminders to "open" whenever you wish.