Move a reminder to another list on iCloud.com
When you move a reminder to another list, the change appears on all your devices with Reminders turned on in iCloud settings.
Note: If you’re using updated reminders, you can’t move a reminder to another list on iCloud.com. You must use the Reminders app on a device with iOS 13, iPadOS 13, macOS 10.15, or later.
Go to icloud.com/reminders, then sign in to your Apple Account (if necessary).
Select the list that contains the reminder you want to move, then select the reminder.
Tap Details, tap the List pop-up menu, then choose a different list.
Tap Done.