Using vSphere Web Client to clean up a VMFS datastore that was temporarily extended across 2 drives
If you use thin provisioning in your home lab, it's quite likely you'll accidentally fill one of your drives to 100%, even if you have drive space warnings set. Hitting capacity has the effect of pausing your beloved VMs that use that datastore, forever. Well, at least until you come up with a way to grow that datastore. This situation is annoying, but temporarily losing access to your data sure isn't anywhere near as crummy as actually losing data would be.
One of the easier ways out of such pickles is to add a VMFS extent by inserting a blank drive and adding it to the full VMFS datastore. This way, ESXi will realize the VMFS is no longer 100% full, so you can then unpause the VM. Once that VMs is stood back up, before you do anything else, you should do a Storage vMotion to get all data off that temporarily enlarged datastore.
With the stage now set, you now know where this video picks up. Yes, I actually filled my Western Digital Red 6TB drive to capacity. In this actual home lab situation, I'm using vSphere 6.0 / ESXi 6.0 on vZilla, and you'll hear me narrate my use of the vSphere Web Client as I clean up my mess. You'll see me unmounting the no-longer-needed extra drive, then physically ejecting that drive. Those procedures have changed a bit from what you may be used to with the C# vSphere client.
Even if you just want to get some familiarity with vSphere Web Client and managing storage, including finding the "Devices Backing" menu seen pictured above, this video may be helpful. Enjoy!
TinkerTry How to use PARTED Magic's Secure Erase to restore performance of your home lab's abused SSDs
Hitting 100% capacity on older SSDs may hurt their performance, the above article and video shows you exactly how to resolve that situation.
VMware KB 1017662 Growing or expanding a VMFS volume or datastore (1017662)
VMware KB 2004605 Unmounting a LUN or detaching a datastore/storage device from multiple VMware ESXi 5.x/6.0 hosts (2004605)