"Kicks down ladder" is a phrase that typically connotes a negative connotation, as it is often associated with acts of sabotage or betrayal. Some synonyms for this phrase could include "undermines," "sabotages," "backstabs," or "disrupts." These words all carry with them an implied sense of malicious intent, and suggest that the individual who is performing the action is actively seeking to harm or undermine someone else. Additionally, synonyms such as "topples," "overthrows," or "upsets" could also be used to describe the physical action of knocking over a ladder, without necessarily carrying the negative connotations associated with the original phrase.