"vmguest.iso" is the installation media for "Hyper-V integration components". Installing the Hyper-V integration components into guest virtual machines hosted in Hyper-V installs drivers that optimise the VMs interaction with the host.
The iso file would only be used when you select the install integration components" option in virtual machine connection for a VM. It is then mounted as a DVD drive within the virtual machine and a normal software installtion of the components run from the dvd. After that, the dvd image can be dismounted ad is not needed again for that VM.
So in terms of functionality, if you are not running Hyper-V, you would have no use for that file.
Whether or not manually removing the file would interfere with future maintenance of Windows I can't say.