Right click a folder containing the avatars and press properties. There should be a section called "Attributes" that has two check boxes, the top one will probably be checked. Check the bottom one that says "hidden."
Now if you want to find it again, go to the start menu and search for "Folder Options" or open "run" and type Folder Options into the box. There in Folder Options you will get the option to unhide all hidden folders and change the folder back.
And for improvising, right-click your folder, go to Properties, go to Customize/Personalize, click change icon and select a blank icon. Then, name the folder like this:
Right-click your folder, click rename and do this:
Hold alt and type in
0160 with the numpad. Press Enter.
To make sure that no one finds your avatars via search, name them random letters. Also, try putting your folder in some place in your hard driver rarely visited.
AlternativePut your avatars in a pen drive or a CD. It's safer and you'll surely get in no trouble.