removing button skins for toolbars

This question is in regards to the custom toolbars that you can separate
from the task bar...  some of the skins I have seen have individual buttons
skinned for each icon. I like the buttons to appear only when you mouse over
or click on them.  What must I do to eliminate these buttons?  I have tried
editing the image files for the buttons by clearing the first button in the
image.  Apparently, though, it isn't as simple as that.  When I run the
skin, the button is still there, and it has simply expanded the size of
them.