Welcome! This forum has a treasure trove of great info – Scouters helping Scouters! Just a heads up, though - all content, information, and opinions shared on this forum are those of the author, not the BSA.
You can ask the other adult leader to go to your [Scout]'s Connections page in Scoutbook, click on their name, and remove their erroneous “Parent / Guardian” connection.
Or you can ask your local council to remove the incorrect parent connection.
Although @JenniferOlinger didn’t mention it explicitly, there’s no way for anyone other than council or the erroneously connected adult to remove their Parent/Guardian connection in Scoutbook.