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 view page by clicking the 3 dots in the right-hand corner and then move to bin:
Alternatively, delete assets in bulk by selecting assets from the browse page and clicking the bin icon:
Assets that have been moved to the bin will not be searchable or discoverable by other users.
Assets remain in your bin for 30 days, unless restored, before being permanently deleted from Dash.
Related article: How can I restore deleted assets?