Cannot edit athlete's name

had to delete them from the built-in wp users.
Updating their name from wp users does not work.May be if you login as the user but it is hard for admin to login for 300 members to manage such stuff.

There is a table called wp_usermetawhich contains parameter = value type data. Look for first_name and last_name values in the meta_key field. The corresponding useridties to the wp_user table. Probably not the answer you wanted, but hopefully better than having to log in as every user!