Immovable object vs. irresistable force

Step one in the dojo build: Remove the re-enforced concrete pillar from the future mat space. This lump of concrete and steel has been here immovable for over 30 years since the house was first built and is fact the top of one of the major support pillars for the whole building. It hasn't visibly weathered in any way at all (good news for the house) and I suspect will be an absolute bitch to take the top off. My tools - angle grinder, trusty sledge hammer and a relentless inability to accept defeat!

The tricky part is that I absolutely do not want to crack this pillar below the level of this floor for obvious reasons. So getting this wrong could put a rather serious dent in all the very expensive renovation work which has been going on the in the house below. I can't just smash this thing with abandon. This needs somewhat of a surgical approach albeit applied with a sledge hammer!...

...3 hours in and I have confirmed 2 things I suspected. One - this thing is packed with 20mm steel bars, no wonder the house has stood up to 30 years of Okinawan typhoons and tropical rainstorms so robustly. And two - this job is going to take 2 or 3 days and plenty of blisters and plasters!

well at least the weather is fine and I'm not stuck behind a desk;)