Illustrated guide to cutting rotted bulb?

[RandomGemini]

I'm learning my lesson. No more hardware store orchids!!!

The oncidium my husband brought home has a yellow/orange mushy spot on one of its bulbs. The bulb doesn't seem to have any new growth coming out of it. So I think the best thing to do, is remove it. I haven't watered it since it came home, out of concern that it was overwatered at the big box store. It needs to be repotted, as the pot it's in is a tad small. Now that I've seen this, I'm thinking that repot can't wait for the 7-10 days it will take my thumb to heal from the last time I repotted a hardware store orchid that had rotted roots. Even though I've had this experience with hardware store orchids before, I'm still surprised this one managed to rot as it's potted in a mix that looks like lava rock, charcoal and perlite.

Is there a guide out there somewhere that can tell me how to remove the rotted bulb safely, maybe with photos or even a video? I'll probably have to have another family member perform the surgery for me and would really appreciate a step by step guide for them to follow.

Thanks!