Solution 1:

You need to either

  • Extend DataStore size (can be done online) or
  • Storage vMotion some of the other VMs off this Data Store.

The ultimate goal is to free up space on the DataStore so you can unfreeze VM. And by the way - freeing space from the OS level won't help you.
If your vmdk is thin - it will grow in size over time, but will not shrink when you clean underlying OS.
There are some tricks to reduce vmdk size again available, but those require bringing VM down (not online process).

Solution 2:

While I've not run in to that particular problem before you might try

  • Free up some space and try again, perhaps enough for the consolidate to work by
    • Delete some old log files. I see that you have over 2GB in logs in that one folder alone.
    • You may find that shutting down some VMs will free up some space taken by the *.vswp files, while they are shut down.
    • What Dmitry Zayats suggests about extending the datastore to make it bigger or moving other VMs off that datastore.
    • If all else fails, move the VM to a datastore with enough space, then see if you can get rid of the snapshots. Note that since the machine is not running you can use a few different methods of moving the VM.
  • Try the "Delete All" button in the snapshot manager instead of consolidate.

Note: Deleting data at the guest OS level will likely only make the snapshot files bigger, as it makes the snapshots more different to the previous snapshot than before.

Some light reading

  • How to consolidate snapshots in vSphere 5.x/6.x (2003638) - basic howto
  • Unable to delete the virtual machine snapshots (2017072) - make sure your backup software has let go of the snapshot
  • Snapshot consolidate option is grayed out in vSphere Web Client 5.1 and 5.5 (2058138) - try the windows client instead
  • Troubleshooting when virtual machine options are grayed out in vSphere Client (2048748) - command line stuff (danger: here be dragons. Instead of deleting snapshots you may end up doing a "go to snapshot" by accident)