The way I’ve handled this in the past is by ending the scout’s membership (rather than waiting for recharter to process and do it “automatically”).
First, I make sure that at least one parent has connected to the scout’s account and has their login information for Scoutbook.
Once I know that a parent is connected, I remove all non-admin unit-related connections (leaders, parents with View Profile, etc) to the scout (i.e. using Connection Manager and the Feature Assistant Extension, click on the scout’s name and uncheck all of the connection types). Then, I open the scout’s Connections page in one browser tab and the scout’s Membership page in another. I put an end date on the scout’s membership with our unit on the Membership page. I swap to the browser tab with the Connections page open, and start ending all of the unit admin connections (which should now be severable since the unitmembership has ended). The last one I remove is my connection, which will boot me out of the Connections window. The scout is now a free-floating database entry, with the only connection via his or her parent.
I think that this still works.