With Google Ad Editor, you can easily do so. See this article for more detailed information.
However, in web interface, it is not so easy. Please follow the steps below:
- In “All Campaigns” level, click “Audiences” in the left panel.
- In the right part, in “Demographics” section, select the wanted demographics, such as “Age”, then click “Show Table” in the bottom.
- Then, in the top-right corner of the table, click “More …” and then select “View Exclusions”:
4. Then you will be able to edit the age exclusions at the campaign level:
5. If you want to edit the exclusions at the ad group level, then simply click “Edit Demographics” button in the right-bottom corner of the “Demographics” section:
6. That’s all!