As all the guys said to you, there is no such thing as a "Reboot" button for virtual machines, neither of the available options offer that, not even Virtualbox, VmWare, Hyper-V...
This is done inside the VM, like it it was a normal computer, you got to start menu and look for shutdown options and then choose reboot... there cannot be a reboot button simply because it must need to send the reboot instruction to the VM, so the OS closes all it's tasks, frees memory and shuts down, and afterwards, commences all the booting process again.
If you use Hyper-V, @
Kari already gave you an option so you can reboot your machines all at once, but still, that resets the machine, doesn't trigger the reboot process, which is entirely different, if you restar machines willy nilly, you can cause many errors and problems with services and OS components that need a shutdown instruction to not fail.
I use VMWare... and not even me has a button for reboots... I think that doesn't exist...