This is applicable only to KVM based VPSes on CrownPanel -- Also, you can always setup a VNC server inside your VPS and/or enable RDP (if using Windows) as needed.
Login to CrownPanel at the following URL: https://crownpanel.com
Click on the "Manage" button beside the VPS you wish to manage
Switch to the VNC tab and click on the "Launch VNC" button to launch a browser based VNC session or if you wish to use a desktop based VNC client, click on the "View VNC Details" button
To disable VNC you can see the following guide, Disabling VNC on CrownPanel
To restart VNC you can see the following guide, Restart VNC on CrownPanel