Using a flap sand disc to remove the finish from a closet door
I wouldn't recommend that no.  As mentioned in the other post, the layer that gives the doors their wood grain appearance is likely very thin (unless they are solid wood doors, which I doubt).

So the main drawbacks of this method are:


The disc sander will leave a spiral pattern in whatever you sand with it.  I would never recommend this for wood (metal yes)
Unless you are very very careful, you will likely gouge the wood to the point the top layer is no longer nice at all.


What do you intend to do after you remove the finish?  Stain/Seal, Paint?

Edit: You can attempt to utilize a gel stripper to remove the finish.  Now this would have to be done very carefully.

One or two layers should eat through the finish pretty quickly.  Do NOT let it sit for very long on veneer as it can penetrate and eat through the glue meaning...no more veneer.  (I would like to put this disclaimer up front:  If not done carefully and correctly (and potentially even then) this can cause veneer to peel off.

If you go this route don't leave the stripper on long...30 seconds to a minute tops, then scrape it off and wipe off any remainder.  If you can get through the finish, you can use sanding sponges and get the stain layer off by hand easily enough,