[QUESTION][REQUEST] How to remove a block?

You touched on a few questions here, but to get to your first in your headline; reference the BlockManager api docs here

e.g. BlockManager.remove('custom-block-id')

You're mixing too much stuff in one question and without any context

@artf I just wanted to remove the new block that I added via editor.DomComponents.getWrapper().getEl().insertAdjacentHTML();