IS Retail - discontinuing an article for a certain sales area

HI,

For an article, say article 123456, we can process a sales order for a certain sales org / distribution channel. say 1000 / 10. however, we want to discontinue this process. How do I set this up in the system, so it won't allow anymore an article 123456 to be sold under sales area 1000/10. I'm thinking of changing the article master? But how should it be done?

Thanks in advance !