Removing Develop presets from Existing images

Clearing history has two different senses - keeping the image as it is but foregoing any ability to return to its earlier states; or, returning to an earlier state of the image and deleting all subsequent editing as if that had never happened.

I think it is more useful to concentrate on the effects of history steps, and on how they relate to what you want now, rather than on the steps themselves. On that understanding, yes there are techniques that make use of the History panel. Say you want to bring some particular earlier adjustments back to the fore (you now regret having altered them further in the meanwhile) - but you don't want to eliminate other work you have also done since. So you won't want to fully roll back the image. 

When you click back to an earlier history state you can still return to the latest state again, provided you haven't made any fresh adjustments while this earlier state is showing. But you can Copy Settings from that earlier state - selectively, putting a checkmark against just the particular kinds of adjustment you want to retrieve. Then click in History to return to your latest editing. Then Paste Settings. This adds a fresh history state applying those checkmarked adjustments anew. And only those.

This is not a matter of airbrushing the past. It is about negating the bad results from an event, by making things right 'in the present'. These new actions call on, and reinstate, how things were in the relevant aspect(s) prior to that unwanted event. So indirectly,effectively, things HAVE been made "as if" that one unwanted event had never happened - but, no time machine is required. Just a knowledge of History.

Once you have multiple images successfully selected, the Previous button should switch to Sync. Perhaps the other images had been de-selected somehow.