Hi, Nicholas.
You should delete all the data you can via wp-admin (e.g. go to wp-admin > Events > bulk select all and delete… same for Organizers and Venues). Note that doing this before deleting the accompanying postmeta would leave orphaned postmeta.
Via the database, you’ll also want to delete all options with an option name starting with “tribe”.
After this, search anything with “tribe” in your entire database and handle that as you desire.
This may not be comprehensive but should be pretty close if it’s not.
Of course, we always recommend restorable database and file backups before modifying anything on your site.
Please let me know how this goes for you.