Unity 3D - 2019 - Large Directories within Project Folder - Version Control issues !!

Large DIR's see in the Project Folder - all DIR's under Library
1/ ShaderCache = 300MB
2/ PlayerDataCache = 242MB
3/ metadata = 309MB
4/ PackageCache = 10MB as of now - may increase ??

As seen within one of the Files at path - C:\Win_UnityProjs\unity3d_car_terrain\sueblackman_book_2_3d_car\Library\metadata\78

FileName = 780611a67e8e941a2b3aa96e5915a793.info

It refers to a Asset Prefab within the Standard Assets at path =     path: Assets/Standard Assets/Environment/Water/Water/Prefabs/WaterProDaytime.prefab

mainRepresentation:
    serializedVersion: 3
    name: WaterProDaytime
    thumbnail:
      m_Format: 0
      m_Width: 0
      m_Height: 0
      m_RowBytes: 0
      image data: 0
      _typelessdata: 
    guid: 780611a67e8e941a2b3aa96e5915a793
    path: Assets/Standard Assets/Environment/Water/Water/Prefabs/WaterProDaytime.prefab
    localIdentifier: 100000
    thumbnailClassID: 1
    flags: 1
    scriptClassName: 
  

I doubt i have used this asset in the current project - my mistake seems to be having imported and retained all assets from within the standard assets . 

Requires cleaning the standard assets and retaining only the ones being actually used !!