We have a Windows 7 virtual machine on VMware Workstation 11. The VM is now encrypted (using Workstation) but wasn’t always. The VM has confidential information on it and as we no longer need it, we would like to securely delete the full VM. What is the safest way to securely delete the whole VM? Would it be to secure delete all files in the VM folder?
VMSphere Documentation Centers recommends zero-ing out the entire contents of the file before deleting. While I understand you are running, VM Workstation 11 the same logic would apply. It is recommended that you boot the VMFS from CDROM/ISO that contains a program to wipe a hard disk (e.g. DBAN, etc.), wipe the entire contents then delete the .vmdk.
For further assurance, you could follow the directions of @Tim and @John. You could use a program like CsCleaner, sdelete from MS SysInternals, or other file deletion tools to delete the .vmdk. However, if you will continue to use the physical hdd, it is important that you use full disk encryption until the time comes to decommission the physical drive, when you securely wipe & destroy it.