Hi there “gevorg2006”,

Thanks for your question “How do I add negative keywords to my Yahoo! ads?”

You can add or delete ad group-level excluded words in the Ad Group Tactic Settings page. This is available from the Ad Group Settings button dropdown menu in the Ad Group Details page, as well as from the Ad Group Settings page.

Account-level excluded words can be added from the Account Tactic Settings page, which is available from the Account Summary page in the Administration tab.

Just a reminder, you may need to click the [show] link to expose the entry field.

Hope this helps,

YahooPete

Thanks.
I found it.
It's a bit hidden though.
For anyone else. You should click "Edit" on Tactic settings then only you will see "Exclude Words".