As an editor, I want a way to remove selected Content Object from the "embed" Block Attribute if this attribute is not required.
Currently, I can select another Content Object, but I cannot remove the selection in any way. I can remove the block entirely and create a new one of the same type from scratch, but my custom block can have a lot of other attributes and I would have to enter the values for these attributes again.

One option to implement this improvement would be to add "remove content" button, similar to what has been done in the "Collection" block.

An example implementation of a custom block with the optional "embed" Block Attribute can be found in the attachment.