Can you login without an email?

I would like a user without an email to be able to register/login, is this possible?

Technically, no, as the email field is required for a database connection. However, in very specific circumstances where you could ensure that actual email messages are not required to be delivered to the end-user then you could consider registering the user with a unique email address generated automatically and that is not associated with a real email inbox.

Have in mind that the above would also mean you likely not be able to leverage higher level libraries where the assumption is that the end-user would have a real email inbox. For example, sign up with Lock expects an email to be provided; you could also not leverage reset password flow as that requires email. Having said that, you could implement your integration with lower level libraries or direct API calls in such way that the fact that the end-user account had a unique email address that does not map to a real inbox is transparent for the end-users.

In this situation, you would also have to enable the option to require a username in the database connection because since the user would not know about this supposed email address they would have to login with a combination of username and password.