I am working out of a guided landing page and I unable to clear some elements. For example I want to delete the "Hero Poll' element and the "clear element' option is not available.
By clear do you mean empty it? If it says "Unassigned" it means you have not yet added a Poll there. If it is unassigned it should show up as a blank space in the template.
If there is a poll there, maybe try refreshing the page and try clearing it from the actual space it is occupying instead of in the right-hand menu.