Credit belongs to https://superuser.com/a/871037/136936
- Ctrl+Alt+Del won’t work with nested RDP(remote desktop protocol) sessions
- Ctrl+Alt+End won’t work with nested RDP sessions
- The only way to make it work is to run “osk.exe”(On-Screen Keyboard) through admin command line and Hold the Ctrl and Alt key from your current physical keyboard then use mouse to click the Del key from OSK UI keyboard
Since this is the third time I need to search this special treatment, mark it down. 
