Not require password on user signup
What you want is the deferPublicRegistrationPassword config setting.

By default, Craft will require a 'password' field to be submitted on front-end, public user registrations. Setting this to true will no longer require it on the initial registration form.
If you have email verification enabled, new users will set their password once they've clicked on the verification link in the email. If you don't, the only way they can set their password is to go through your &quot;forgot password&quot; workflow.