how to undo makemigrations django

# The migration you want to undo is 0011_last_migration
# The migration right before it is 0010_previous_migration 
python manage.py migrate my_app 0010_previous_migration 

# Then you could delete the migration that you don't need (0011_last_migration) in the migration folder 

# list all migration names like this
python manage.py showmigrations my_app