Kicking off is a phrase commonly used to refer to starting or commencing an event, project or activity. Its antonyms would, therefore, be related to the words 'stop', 'finish' or 'conclude'. For example, rather than 'kicking off' a project, you could 'finish' one, or instead of 'kicking off' an event, you could bring it to a 'close' or 'conclusion'. Other antonyms could include 'end', 'terminate', 'cease' or 'complete'. It is important to recognize the context in which this phrase is being used, and to choose the most appropriate antonym based on that context.