Many cartridge bearings can be disassembled. Remove the seal, press out the ball spacer, move all the balls one side, then lift out the inner race. Reassemlbe in the reverse order. That's usually not necessary. Just remove the seals, flush out the bearing with solvent, then reapply grease.

In removing press fit BB bearings, you often need to press them out by applying force to the inner race. This can damage (dent) the balls and races if the required force is high enough or is unevenly applied. If I need to press out bearings, I always replace with new. Of course, when installing, you want to push on the race with the press fit and not on the other race.

I found it useful to periodically add grease to my BB30 bearing every 1-2k miles or so. Remove the crank, remove the outer seal of the bearing, push in some compatible grease, reassemble. These bearings often have loose seals and little grease to make the spin more freely. This allows water in and grease out greatly shortening their life.