If you have many virtual machines, the Control Center window may get overloaded and inconvenient to work with.
You can configure Control Center to show the minimum information - only virtual machine names and icons. To do so, click the Parallels Desktop icon in the Dock and choose View > Compact View in the macOS menu bar.
Or if you're using Parallels Desktop for Mac Pro Edition, you can change how your virtual machines are arranged. Click the Parallels Desktop icon in the Dock, click View > Arrange By and choose how you want to list the virtual machines.