To empty or delete the contents of a file. You can use Clear-Content command, and provide path to the log file.
Clear-Content -Path .\Test.log
You can also use Set-Content to clear contents of a text file. By setting the content to an empty string.
Set-Content -path .\Test.log -Value ""
You can use New-Item command with -Force argument to delete content
New-Item -ItemType File -Name Test.log -Force
Just testing some markdown works