A bit of a hassle, but you can revert the VM tools v10 back to vmx-9 which is editable via the vSphere client (no need for vCenter):
1) Open up a SSH connection to the host.
2) Go to the folder for the VM.
3) Edit the .vmx file with vi, i.e. vi MyVM.vmx.
4) Change virtualHW.version = "10" to virtualHW.version = "9".
5) Remove the VM from the inventory by right clicking it -> Remove from inventory. (Do not delete from disk!)
6) Open up the datastore browser (right click the datastore -> browse) and go to the folder for the VM.
7) Right click the .vmx file and choose add to directory.
You can now edit the settings via the vSphere client and you do not need vCenter at this point.
Hope this helps,