July 31, 2019
If you’re inundated with blocks that are not being used in your Theme template, and you would would like to hide unused blocks; use the default settings within WordPress core to remove the blocks from the “Add Blocks” option.
To do this, use the “Show more tools & options” menu option:
Select Block Manager (under Tools):
You can hide Blocks one at a time, or in batches by checking off the Category they appear under.
Several online resources suggest using plugins like Advanced Gutenberg Blocks or Disable Gutenberg Blocks to accomplish this. However, these plugins can throw several errors following updating WordPress core, even though the blocks are successfully hidden.