So reading further into this, seems the log cannot be cleared (in fact there seems to be some kind of EU rule/regulation that stipulates this). It is probably that it could be used as evidence in a criminal case, hence there is no option for someone to wipe it and in essence destroy evidence. What I believe happens is once the log is full, the panel will overwrite the oldest logged event with the new event, and so on. So there is no need to be concerned about running out of log memory. I assume the panel just warns you at 90% and then possibly 100%, so you are aware the old events are going to start being overwritten and therefore lost.