There's currently a bug where you can remove any block you want by using signs, including indestructible blocks such as Bedrock and End Portal Frames. How it works is if you place a sign on top of a bottom-slab with a block on top of it, it will replace that block with the sign. Meaning you can break Bedrock with it. You can also do this sideways by placing a sign on the side of another sign.

Players who have figured this bug have been using it to break through Bedrock, replace End Portal Frames.