Hello,
I can help you out with this.
I find if I remove the 0 from Regular Price ($) that is removes the word Free.
I noticed some events such as this one do not have the word free in there, so maybe some are done that way already?
http://events.vincoglobal.com/event/alyssa-reinoso-marketing-associate-crowdonomic-crowdsourcing-crowdfunding/
To remove it from an existing event go to the Event Edit Page.
Find the Event Ticket you would like to remove free, hover over it and click the link “Edit in WooCommerce” (it did not remove it for me when I edited the ticket in the event edit page)
Then remove the 0 from the Regular Price ($).
Let me know if that works for you.
Thanks