Who gets the luxury of 1 level these days? There are times when I am Google Remote Desktop into Parallels Remote into RDP. Not great but Windows reality.
I needed to change my password in one of these fun situations where Ctl-Alt-End the normal RDP substitute for Ctl-Alt-Del won't work.
I got this from: https://social.technet.microsoft.com/Forums/windowsserver/en-US/9c2ea402-087a-40a0-83de-170b49fdaac5/how-to-change-password-in-rdp-session?forum=winserverTS
Use the On-Screen Keyboard (osk.exe). You can press Ctrl-Alt-Del virtually!
Holding ctrl-alt on the top-level machine and clicking the 'del' in the desired level OSK works.
Once the app is open, hold ctrl+Alt on your keyboard, then click on the del key in osk.exe.