You would have to first, disable the avast self-defence.
But me I would want to know why it has grown so large, mine is tiny (7kb) and I suspect that you have tweaked the Report settings, by including Soft errors and or OK items, Skipped items. The inclusion of these would greatly increase the generated data, see image.
In the avast Settings, Maintenance section I also limit the duration data is retained and reduce the maximum size of the log files and debug logging is unchecked by default.