To hide items with a specific attribute, a particular product group or assortment in the Portal, you can use an exclusion filter. Go in the CMS to Core-portal basic > Settings > General and follow the steps below:
1. Select the appropriate product group.
2. Click the green plus to link the product group as an item filter.
3. Check the Use item filter to exclude items option and save the changes
This will prevent all items associated with the specified assortment or group from being displayed in the Portal.