I use a modified a StewMac fret puller and two single edge razor blades to remove a fret from an ebony fingerboard on an older Martin. HD-28. Sliding the straight razors under each side of the top of the fret being removed helps spread the downward pressure from the head of the fret puller when it lifts the fret. This helps minimize chipping. I only had three little chips to glue back in.
I used several cylindrical abrasive bits in a rotary tool to expand the inner area in the StewMac fret puller to make the angle at the edge sharper. I also ground off some of the sides to make the whole tool a bit narrower and smoothed and polished the head.
https://www.stewmac.com/luthier-tools-and-supplies/tools-by-job/tools-for-fretting/pullers-nippers-sizing/stewmac-precision-fret-puller