I just did this procedure. Didn't have the right tool to uncrew the
saddle from the drain. So... A pro took a cold chisel and went to work.
If you don't care about using the tub again a cold chisel is the tool.
Note: this follows the "bigger hammer" rule of home and auto repair.

Tom wrote:
Hire a pro? The drain flange could probably be unscrewed from above...if you
had the right tool for the job. HTH Tom
Work at your leisure!