VMware

In the list of virtual machines, select the virtual machine you want to delete and right-click on it (or press control-Klick). In VMware Workstation, select "Remove", in VMware Player "Delete VM from Disk" or in VMware Fusion "Delete". The virtual machine cannot be removed while it is running, but must be turned off first.

VirtualBox

To remove a virtual machine from VirtualBox, select Machine → Remove from the top menu as shown:

VirtualBox asks if you want to delete the machine only from the VirtualBox machine list or also the actual virtual machine file. This applies to the machine file in the VirtualBox directory, and does not affect the ova file from which the virtual machine was originally imported.