How can I access the configured Log4J appenders at runtime?

Appenders are generally added to the root logger. Here’s some pseudocode

// get the root logger and remove the appender we want
Logger logger = Logger.getRootLogger();
Appender appender = logger.getAppender("foo");
logger.removeAppender(appender)

// when we want to add it back...
logger.addAppender(appender);

I’m pretty sure you can do this on other loggers than the root logger as well, though I’ve never tried that.