I believe there also has to be a removal of the fill valve so that no oil is mistakenly delivered to a decomissioned tank
Someone my wife knows had their House up for sale and was in already in Contract with someone. Person next door calls for an oil delivery and driver goes to the wrong house by mistake. Wifes' Friend was not home and driver pumps oil into the fill pipe, but there was no tank inside. They had removed the tank (maybe converted to Gas, I don't know) but did not remove the pipe. They now had all this Oil in their Finished Basement!
I don't know what happened, but I'm sure it was not fun.
Bill