Another option can be that if the ILoggerFactory implementation also implements
the Closeable interface [1]. Then client code need not depend on specific API
but can be generic 

import org.slf4j.LoggerFactory;

if(LoggerFactory.getILoggerFactory() implements Closeable){
   ((Closeable)LoggerFactory.getILoggerFactory()).close();
}

Thus if any of the bindings require cleanup then there respetive factories
implement the Closeable interface e.g. Logback

[1] http://docs.oracle.com/javase/7/docs/api/java/io/Closeable.html