Django models migrations: error--trying to add a non-nullable field - django

Question

When I makemigrations to my models, the terminal gives a warning of: "You are trying to add a non-nullable field, etc" and asked for 2 options. I must have made migrations 7 times--should I delete the "0001_initial.py", "0002_auto file" as well as the db.sqlite3? I don't need to keep the database information I inputted since I merely only did tests to see if the models worked---I just want to make sure I don't delete the database itself so I can further test my models to see if they're working. Can someone please verify the specific files I would need to delete so I can make migrations? Your help will be much appreciated!
So far my migrations folders look like this: 001_initial.py, 0002_auto file, 0003_auto file, 0004_auto_file, 0005_auto_file, 0006_auto file, and finally 007_order_buyers file----the last file concerns me--I think it's bc I must have clicked option 2. I just merely want to be able to makemigrations and I am wary of my models not working if I delete important files.
models.py
class User(models.Model):
first_name=models.CharField(max_length=100)
last_name=models.CharField(max_length=100)
email=models.CharField(max_length=100)
password=models.CharField(max_length=100)
created_at=models.DateTimeField(auto_now_add=True)
updated_at=models.DateTimeField(auto_now=True)
class Order(models.Model):
full_name=models.CharField(max_length=100)
cc_number=models.PositiveIntegerField()
exp_date=models.PositiveIntegerField()
cvc=models.PositiveIntegerField()
buyer=models.ForeignKey(User, related_name="bought_tickets", on_delete=models.PROTECT)
created_at=models.DateTimeField(auto_now_add=True)
updated_at=models.DateTimeField(auto_now=True)
class Ticket(models.Model):
venue=models.CharField(max_length=100)
quantity=models.PositiveIntegerField()
price=models.DecimalField(default=25.00, max_digits=5, decimal_places=2, null=True, blank=True)
loop=models.CharField(max_length=100)
purchaser = models.ForeignKey(User, related_name="purchases", on_delete=models.PROTECT)
order=models.ForeignKey(Order, related_name="orders", on_delete=models.PROTECT)
created_at=models.DateTimeField(auto_now_add=True)
updated_at=models.DateTimeField(auto_now=True)

Answer 1

Running makemigrations doesn't do anything to the database, so you can back anything out easily if you haven't run migrate. All that makemigrations does is to create a file. If you don't like it, remove it. When it gives you the error about non nullable field, the options are pretty explicit. Just read them:
You are trying to add a non-nullable field 'foo' to bar without a default; we can't do that (the database needs something to populate existing rows).
Please select a fix:
1) Provide a one-off default now (will be set on all existing rows with a null value for this column)
2) Quit, and let me add a default in models.py
Select an option:
If you select (1), the cli will next prompt you to submit a default value. After you do that, it clearly tells you that it has created a file, and tells you the name.
If you select (2), nothing happens. They're leaving it up to you to fix the problem, which you can do in the model by either making the field nullable (add null=True in the field definition) or giving it a default (default=...).
I would suggest taking a look in those files to make sure you understand what they are doing. It's all pretty straightforward. Any of them which have not been run yet can be changed. You can edit them directly, or remove and regenerate them.
To see which ones have been run, use showmigrations.