Open Run a run dialogue (WinKey+R), type ‘Control Userpasswords2’ and hit Enter to open the User Accounts Properties box. Open the Advanced tab, and in the Secure logon section, click to clear the Require users to press Ctrl+Alt+Delete check box if you want to disable the CTRL+ALT+DELETE sequence. Click Apply/OK > Exit.
If the option is greyed out:
Run ‘secpol.msc’ and hit Enter.
In the left pane, select Local Policies > Security Options. Now in the right pane, double click on Interactive logon: Do not require CTRL+ALT+DEL. Enable the policy as per your requirement, click Apply/OK and Exit.