Removing Chair Backs for Reupholstering?

Depends. In any case the doweling is not likely too long. I'd first try drilling a small hole with a tiny bit into the doweling, then use the drill bit while in the hole to see if it is loose. If not, and if it appears to be glued, you may have to use a large bit to drill it on out.

Problem is that you need to determine how long the doweling is and how deep the screw it so you won't damage the screw head or you will have to drill it out too and then replace the deeper hole with new glued dowling and have a MUCH bigger job than you intended.

I'd just be VERY careful using the tiny bit, not drilling too deep, then perhaps on one of the holes put your drill in reverse, WITHOUT pulling out on the drill, to see if it will back out of the hole in this manner.

Another option is to use an eye dropper or spoon a few drops of water on the doweling, IF you determine it IS glued, so that the glue, which is likely waterbased Elmer's type wood glue, will soften and come on out after letting it sit for about an hour.
Don't over water it or it might swell the hole tighter.
If you do over-water, let it set in a dry place for a week to dry out and start over withOUT water.

Good luck and God bless and help you. : )

Are you sure there are dowel rods covering the screws? The screws may be covered by wooden buttons. This is usually what is done. Use a thin sharp object, like a paring knife or ice pick, to get under the button. It should then pop off.

Is the chair fully upholstered or just the back? If it is fully upholstered you do not remove the back.
asellars AT roadrunner.com