It is not possible to hide the standard attachment type within ticket's attachment facet.
SAP Cloud for Customer.
Reproducing the Issue
Go to the Service work center.
Go to the Tickets view .
Search for ticket XYZ1 (where XYZ1 is the ticket name) and open it.
Go to the Attachments facet .
Go to the Adapt ->Edit Master layout .
Click on button Add ->Local file and select the drop-down option of Attachment Type field.
You can see, there is no option available to hide/delete the available attachment type from drop-down.
Currently it is not possible to hide the attachment type within ticket.
System will show all standard attachment types and it can not be hidden even via adaptation , this is current system behavior.
Attachment Type , Tickets , KBA , LOD-CRM-SRP , Service Request Processing , Problem