You could set this up with a couple extensions.
1) Create Data Source with the name of the current cookie "CookieExample" Select First Party Cookie as the Type.
2) Create Data Source with name like "cookie_example_value." Select UDO Variable as the Type.
3) Create Data Source with a new cookie name "NewCookieExample" and select First Party Cookie as the Type.
2) Add a Set Data Values Extension and configure it like:
Set: cookie_example_value (js) To: Variable -> Select "Cookie Example (cp)" from the drop down
3) Add a Persist Data Values Extension and Configure it like the attached screenshot.
// Delete "CookieExample" Cooke Value
The extensions outlined need to be in the order they are described here. It is a good idea to add (Step 1, Step 2, Step3) to the titles of the the extensions and also use labels so others will know these extensions belong together.
This will read the "CookieExample" cookie if it exists and create a new cookie called "new_cookie_value" cookie. The "new_cookie_value" cookie will equal the "CookieExample" cookie but be defined on the top level domain. Then the JS Code extension will delete the "CookieExample" cookie.
Hope this helps.