If you don't want your customers to see how many tickets have been sold or remain available, there is a setting to hide this on the public page, under 'Page setup'
This is ticked by default
As mentioned in the green text, the availability will show again automatically once the event is almost full, to encourage your customers to book and not loose out.
Here's what it looks like before removing the availability:
And this is what it looks like after removing the availability:
The same is also applied to ticket numbers if this has been set.