Hello Thora,
it is not possible to avoid the creation of a folder when using the skin tag, as this structure is required for the majority of the most advanced features (Spine automatically adding new skins in the correct spot using the correct new image, skin duplication applying a recolor correctly, etc.).
You could edit the position and then the paths manually, but if they're not really in the way of your work, you may also consider leaving them as they are now, you may be happy later when you need to add a second pair of glasses using the same name but different art for example.
A good structure for your case could for example be one that uses this on the layer name, after the [folder:head tag]:
[skin:glasses_0002][slot:glasses] se_glasses_front
