Look inside >:) Here's how to do it: 1. Create a block. I called mine "null" for demonstrational reasons. 2. Put the standalone block (NOT the definition) in your backpack 3. Delete the definition 4. Place back in the block from your backpack. 5. Now you have a block that has no definition. Let's call it a null block!
This is probably gonna get taken down or marked NFE☹️