Q:

How do you remove all data after running syncdb? 

I'm in production and just ran syncdb but I made a mistake and want to delete what syncdb did, including all data in the tables is fine.  Just a fresh start in the databases so I can run syncdb again. 
(virtualenv-2.7)[root@server mysite]# python manage.py sqlclear mainapp | python manage.py dbshell
CommandError: One or more models did not validate:
app.comment: 'poster' defines a relation with the model 'auth. User', which has been swapped out.  Update the relation to point at settings. AUTH_USER_MODEL. 
app.myuser: The field named as the USERNAME_FIELD should not be included in REQUIRED_FIELDS on a swappable User model. 

A:

As J0HN stated in the comments, the best thing to do to start fresh was to actually just delete the database.  I thought it might mess something up, but it won't.  Simply login to mysql. 
drop database whatever_your_database_name;
create databse whatever_your_database_name;

Then simply sync it again with python manage.py syncdb

