After you click on Assets in TeleScope Welcome Page, a faceted search shows up with the number of assets for every filter mentioned next to that filter on the left sidebar under Filter Your Results. If a few assets are deleted from the results, although it does update the count of results on the right section, it doesn't update the counters next to the filters unless a filter is clicked.
This was fixed in Telescope Standard 2020.5. It is recommended to upgrade to this or a later version. If your TeleScope installation has customizations or you're an OnDemand customer, please contact your Account Manager or support for further assistance with upgrading.
Once the version is upgraded, deleting files from the search view will update counters.