You have two real choices here, you can disable constraints on the table. This usually not a great idea as you can end up with a bad data condition if you're messing with data that relates to other tables, but not know the full extent of your schema and it may suit your purposes:
ALTER TABLE [workdemo.no].[dbo].[M06Persons] NOCHECK CONSTRAINT [FK_M02ArticlePersons_M06Persons]
Remember to turn the constraint back on after the delete with
ALTER TABLE [workdemo.no].[dbo].[M06Persons] WITH CHECK CHECK CONSTRAINT [FK_M02ArticlePersons_M06Persons]
The second choice would be to drop and re-add the constraint with the ON DELETE CASCADE option using:
ALTER TABLE [workdemo.no].[dbo].[M06Persons] DROP CONSTRAINT [FK_M02ArticlePersons_M06Persons]
ALTER TABLE [workdemo.no].[dbo].[M06Persons] WITH NOCHECK ADD CONSTRAINT [FK_M02ArticlePersons_M06Persons] FOREIGN KEY(M06PersonId)
REFERENCES <parent table here> (<parent column here>)
ON DELETE CASCADE
Based on your FK name it looks like your parent table is M02ArticlePersons and the parent column is M06Persons.
If you did not author this schema please try to consider why the constraints may be present, and understand that violating them in this manner may have unintended side effects.