Although, surprisingly, there is no built-in way to clear the statistics for a specific website (very useful if, after a period of testing, a website is ready to go live; or after any major change), there must be a way to do that by clearing some database tables, or something of that sort. How can one reset the statistics of a website without touching other information?
It is possible, but not integrated into the core of Piwik. Have a look at the FAQ: How to - Analytics Platform - Matomo
Thank you. This is what I was looking for.