How do I delete the contents that are included with the installation that I will not use? Some of the contents even date back to MeshVR. I would just like a barebone installation so I can use hub downloaded contents. Not really interested in some of the looks in VaMX either, although the poses are good. 

Would I even save that much space by deleting? 

All the items you are referring to are AddonPackages.  If you open the AddonPackages folder you can see the files.  These are packed files, and you shouldn't edit them to to remove certain items, but you can remove entire packages.  For example you'll see some MeshVR packages.  You can delete all packages except for vamX and vamX Base without major consequences, but when you try to use the Hub to download stuff, things may be downloaded again (if some hub package depends on some MeshVR look or even a single file/texture in that MeshVR package).  For vamX there are large packages with many items, and you can't remove a certain look.  This is partly because of complex dependencies.  For example, a look isn't just the settings that make the female a certain size or shape, the majority of the file size are textures ("skins") which are often applied to MULTIPLE LOOKS.  Also, in vamX we assume a certain set of skins/textures/clothes/etc. for things like random look generation, voice control, random clothing, etc., etc.
In short, you are welcome to non-vamX things from the AddonPackages folder.  It might save space.  You might also just want to buy a USB drive meant for fast file transfer and put VaMX there (you can just copy or move the folder at any time).