Admin users or those with contributor access can delete assets, so they are no longer searchable or discoverable in Dash.
You can delete an asset whilst on the asset details page by clicking the 3 dots in the top menu and then clicking "Move to bin":
Alternatively, delete assets in bulk by bulk selecting assets from the "All assets" page and clicking the bin icon:
What happens to deleted assets?
Assets that have been deleted are moved to the bin. They will no longer be searchable or discoverable by other users.
Assets remain in your bin for 30 days, unless restored, before being permanently deleted from Dash.