Problem
When VMs remain "cp-instant-clone" or "cp.replica" cannot be deleted and the "Delete from disk" optione is greyed out.
Solution
Connect locally on the Horizon View Connection Server.
Open a Command Prompt and navigate to the folder
C:Program FilesVMwareVMware ViewServertoolsbin.
Start the command
iccleanup.cmd -vc vcenter.domain.my -uid administrator@vsphere.local
Delete Orphan VMs