I already suggested to delete the delivery. Whats the problem with that?
I mean if the suggestion from the note does not work, then you can open a call with SAP and tell them that it does not work for you. So they either need to rethink in general or may make this instruction easier to follow. Or you delete the delivery and forget this issue for now.
LT0G has an easy to use selection screen but these lock cases can drive you crazy. I debugged it more than once to get to the reason. This took some hours having all data and information at the screen in front of me.
From your case I don't know much yet, especially not the details about other TOs, about changes in the delivery etc.
And you have no data either to do a LT0G now, you had moved the material with LT10.
So there is no chance to debug now to know the root cause for the lock.
As said, you have two options, contact SAP about clear guidance or to delete the delivery.