How to send Ctrl-Alt-Del
If you want to send Ctrl-Alt-Del key to a remote computer you can use 'Send Ctrl-Alt-Del' entry from the Remote Screen window menu. This feature will work in 'Full control' connection type. You can also use Ctrl-Alt-F12 hotkey for a quick sending.
In some cases another software installed on the remote PC might prevent Radmin from sending C+A+D. In order to solve this issue please perform the following and change the state of this policy (server side):
"Start menu" -> "Execute" - > gpmc.msc
or gpedit.msc
Computer Configuration | Administrative Templates | Windows Components | Windows Logon Options | Disable or enable software Secure Attention Sequence
After you enable Attention Sequence, double click it and set the service to "Services and Ease of Access applications".