1. Create a Custom Audience
Create a custom audience using the Custom Audience API or by uploading a .CSV or .TXT file to Batch from the dashboard settings → Audiences. A custom audience can contain a list of custom user IDs or advertising IDs (GAID or IDFA).
The dashboard will automatically display the number of tokens that match your audience:
2. Exclude it from your targeting
In the campaign's creation form, click on the "Add conditions" buttons, and select Custom Audiences, as below.
Select the Custom Audience you want to exclude in the dropdown menu.
Hit the "Invert" button, a "NOT" label will appear, meaning that the segmentation now excludes the Custom Audience you picked.