That only works if the previous version is at the same revision as the latest. If not, then there is no purging it.
A.2 -> reference to 'some part'
B.0 -> revised
B.1 -> updated to remove reference to 'some part'.
Now you want to delete 'some part'. Can't because A.2 still has a reference to it. Can't purge A.2 because it's the last iteration of the A revision. Now you're stuck. The only option is to put 'some part' somewhere not visible to others.
I imagine it is theoretically possible to go back a create a new version after A.2, but before B.0, but the way most systems are setup, once A.2 is released there is no changing it without a new revision.
