how to remove clear shellac from bamboo shakuhachi?

Hi Chris, Are you sure it's shellac?
Shellac can be removed with denatured alcohol without affecting the bamboo akin adversely. You can wet or soak small areas at a t time and then wipe off. If it's varnish, it will be more difficult. You'll need another solvent, like lacquer thinner or something more toxic.

Using super fine #0000 steel wool dry will work also.

As always, go slowly.

Good luck - Perry

Yes, probably clear lacquer. But with caution I will proceed. I may try dry first with the steel wool on a small patch. Thanks.