尝试 delete:

models.User.query.delete()

来自文档: 返回删除的行数，不包括任何级联.

How do I delete all rows in a single table using Flask-SQLAlchemy?

Looking for something like this:

>>> users = models.User.query.all()
>>> models.db.session.delete(users)

# but it errs out: UnmappedInstanceError: Class '__builtin__.list' is not mapped

Try delete:

models.User.query.delete()

From the docs: Returns the number of rows deleted, excluding any cascades.