I removed mine used both a cutting torch, and grinder with cutoff wheel. I did gouge the bucket a little even put a couple of small holes in the back off it. No big deal after removing the mounts I just welded the gouges up and the holes shut and ground the bucket back smooth, then welded the new mounting plates on and painted it. looks good as new and works a lot better.

I also used the mounts I removed on the the loader side of the SSQA I built to pin it back on the loader. Also I forgot mine had three plug welds in the bottom of the mounts so I just used a large drill bit to drill out the plug welds. The first photo shows the bucket after I removed the mounts and the second shows the mounts I removed reused on the new SSQA. If you have any questions just ask.
http://www.tractorbynet.com/forums/build-yourself/170638-my-attempt-ssqa-kubota.html