Shrinking(decrease) of VM's vmdk size on ESXi 5.5 hosts

Hi

Could anyone please assist how we can reduce the VM's vmdk file size(Thick provision Lazy Zeroed) on ESXi 5.5 hosts

Any methods are there,I don't think so it is possible to reduce the disk by just pressing down arrow in edit settings-->Hard disk section

Much appreciate your help

Thanks&Regards,

Vick