To extract a list of users, go to Configure > Users tab > CSV export.
If you want the list to only include active users (i.e. not archived users), go to Configure > Users tab > filter by Status > CSV export. That way you can also easily remove non-active users (by archiving them).
Need a hand? Contact our friendly Support team via the in-app chat at the bottom-right of your screen, or email firstname.lastname@example.org.