it seems when i sent in the paperwork to the council office for a transfer from one (old) unit to another unit in my council, it was done as a multiple instead of a transfer.
how do i cancel my membership with the old unit?
You probably need to talk to your council registrar to end the spurious registration in the old unit. You might also need to talk to the old unit to have them put an end date on your positions in their unit in Scoutbook (assuming that you can’t end them yourself or that the registrar terminating the registration doesn’t clear them automatically).