How to clear up Avast log.txt

log.txt file in C:\Documents and Settings\All Users\Application Data\AVAST Software\Avast\Spamconf

is constantly growing.

It is more than 2.5 GB now.

How it can be cleared up?

Please (re)search before posting.
Things like this have been explained many times on this webboard already.

https://forum.avast.com/index.php?topic=190794.msg1338970#msg1338970

https://forum.avast.com/index.php?topic=190910

Thank you, Eddy and Pondus.
You both helped.
The problem is solved.

Thank you again for your prompt support.

Will search more next time.