Especially when writing a new load test you work a lot with the jmeter listeners. After a while you don't want old requests to show up in the listener log anymore. Otherwise you have to scroll forever.
My first attempt to empty the listener was to right click on one. But there is no option to reset the listeners (e.g. Summary Report or View Result Tree).
Then for a while I always was just saving my JMeter load test and reopening it to get rid of the old logs in the listener and I was ok with that. Since a co worker asked me about it, I thought there must be a better way and after some investigation I found the answer to how to empty the listener.
Either in the "Run menu", select "Clear" when the according listener is selected. Or you select Clear all if you want to reset or listener logs.
The according shortcuts are Control+Shift+E and Control+E.