Go to Property Manager > Properties > Property Name
From the Property Essentials tab go down to other features and hoover the mouse pointer over the feature you've spelled wrong to the left you should see a gear icon, hover over it and click view/edit.
From the pop up dialogue click edit button
From the drop down combo box hover the mouse cursor over the mistyped item then on the right hand side you should see a pencil and bin icon. Click the pencil to edit then the press the tick icon or use the bin icon to delete.