A subtractive merge is the opposite of a selective merge: it removes from the checked-out version the changes made in one or more of its predecessors. The following scenario is an example of a situation that requires subtractive merging.
The project manager has decided that a new feature, implemented in versions 14 through 16 on the main branch, will not be included in the product. You must perform a subtractive merge to remove the changes made in those versions.