Welcome Email - don't want them sent

How do I disable the welcome email so that it does not get sent to new customers?

admin > configuration > send copy of create email accounts, set to 0

Actually, that controls whether or not you, the store owner, get an email when a new account is created ...

There is not a switch to turn off the welcome email, at this time ...

You would need to edit the module for:
/includes/modules/create_account.php

by copying this to your templates and overrides directory:
/includes/modules/your_template_dir/create_account.php

And comment out the 2 lines that start with:
zen_mail

NOTE: be sure you always check this file very carefully on upgrades so that when you decide to turn that feature back on that you have all of the updates in your overrides file for the future ...