Quote - Is it even possible?

Theoretically it is possible.
You'd have to work out the index of each vertex that you intend to remove so that you can also remove any UV coordinates and polygons.
The remaining polygon data would then need to be modified to take account of the removed vertices.
Every single morph would also need to be corrected for the removed vertices.

If you think about the amount of work involved, the number of files that your going to have to create modified versions of etc., then it's probably not worth the effort.

Upgrading your memory would be the best solution (compare memory cost against the amount of time required to do this)
If you can't upgrade, use REM poses to get rid of unwanted morphs (making your own is simple if necessary). Shrinking textures can also help.