I should do it step by step and in case of invalid situations i should go back to previous state.
Snapshot property of virtual machine is what i am looking for rolling back.
The virtual machine has size of approximately 54 GB and i don't think my harddisks can handle any more space for VM.
First thing i am going to do is shrink spaces on virtual disks, and only way to do is when the VM is on. Because after snapshot i am unable to shrink disks, I should do it before taking snapshots.
Right click the "VMware Tools" icon and click "Open VMware Tools". Select disks and start shrinking.

NOTE: You should have enough free space for shrink operation. Free space in host system should be bigger than virtual disk size.