1. Select the item and then click the Ungroup button in the Data panel.
The item does not move on the Whiteboard however it will no longer be part of the group. You should then move the item on the Whiteboard so that it is no longer positioned on top of the group.
2. Whenever you drag an item that is part of a group, a grey line with the same shape as the original group is shown, surrounding the original group.
If you drag an item from the group outside of the grey line, this item will be removed from the group and the group edge will snap back around the remaining items within the group.