there is a vmdk file in the datastore \ vm folder labeled VM_1.vmdk and is larger than other vmdk file with the same name without the _1. This has consumed almost all of the datastore volume. And starting to cause issues. Is this VMDK needed?
Can it be removed ?
this is a production VM.
According to the file name that you've posted, the VM has (at least) two virtual disks, where the mentioned file name belongs to the second one. So yes these files are required!
Are there other files in the VM's folder with names like "...-00000x.vmdk"? These files are snapshot files, and may be deleted/consolidated from the Snapshot Manager, if - and that's very important - there's sufficient free disk space on the datasatore!