Tearing out 3/4 oak pre-finish that is layed over 3/4 plywood is one option.
This floor is the wider bevel pre-finish floor and has got dirt way down in the grooves and I suspect I won't be able to get the dirt out. With the dirt left behind it will always look bad and won't even come close to matching the adjacent rooms (carpet was pulled out and new sand and finish is going down).

What I have is a kitchen/great room with old pre-finish and adjacent office and living room that was carpet, carper is gone and I am going sand and finish so the colors will match but with the dirty grooves on the existing floor I can't see it every matching up. If that is the case I may as well just pull it up and put all new micro bevel pre-finish down. Aside from labor this would wind up costing less anyway.

How difficult is it to pull a 3/4 2 1/4 width floor up?
Will the subfloor get damaged?
Floor runs several inches under the cabinets, tool to cut flush or close to flush to cabinet?

I expect this may not be necessary if I can somehow get those old grooves cleaned out but to lay a bunch of new floor and refinish the old floor and have dirt in the grooves would be a waste.

I takes almost as long to pull the flooring up as it was to lay the floor.
You will need to get a toe kick saw with carbide blades from Harbor Freight.
Have spare blades in case you hit a nail.
Sometimes cutting across the flooring with a skill saw adjusted to only cut through the flooring will help in removal. You should be able to save the old flooring for re-use if you are careful removing it. It can be sold or given to a friend who wants to pull it up and remove the nails.
The sub-floor will have nail holes, but not be damaged, if you are careful not to adjust the skill saw too deep and only cut the flooring.
If you pull it up to re-use, start at the last row that was laid and work back to the beginning rows. Once you get started it will be fairly easy.

This video offers some tips in what Pete talks about...only if you don't plan on using the old.

https://www.youtube.com/watch?v=DBkTQgyIDp0