liquibase-core/src/main/java/liquibase/change/ChangeFactory.java
public void unregister(String name) {
        for (Change change : new ArrayList<>(findAllInstances())) {
            if (getChangeMetaData(change).getName().equals(name)) {
                this.removeInstance(change);
            }
        }
    }
public void unregister(String name) {
        for (Change change : new ArrayList<>(findAllInstances())) {
            if (getChangeMetaData(change).getName().equals(name)) {
                this.removeInstance(change);
            }
        }
    }
Unregister all instances of a given Change name. Normally used for testing, but can be called manually if needed.