Ok, now I am confused, but I won't explain why it's confusing here because it'll only make things more complicated.

Here's what you need to do:

1. Identify which skin your portal is using.

--> Go to Portals/_default/Skins and see if your skin folder is located there.
--> If it's not, go to Portals/0/Skins and check again. (also check other folders in Portals )
--> If you still can't find it, then I really don't understand because skins can not be stored anywhere else.

2. Suppose you've identified the skin folder, change its name to something different.

3. Revisit your site. Clear all browser's cache to make sure the change is updated. You'll now see the default skin being used.

If all of the above does not work, you can modify the database table, but that's the last resort.

HTH,

Duc