if you have already liked a status update message, you can remove the like (unlike it) by sending a DELETE request to the web address of the status update entry. Here's one easy way to do it with an asynchronous HTTP (Ajax) request using jQuery.
There is no a link to IBM Connections 4 documentation.
Atom API Request Details
|Response||Status Code: 200 OK|
Example using jQuery
Note: console.log can throw errors in IE, they are there for illustrative purposes only and should be changed as required.