Wendy is putting a shed in the back yard. Naturally it requires to be on a concrete pad. Which needs to be dug about seven inches down. Which had a pipe that use to hold a clothes pole in the back yard. Her did not want to be removed.
Just happen a small "Three Inch High Speed Cut Off Tool" from Harbor Freight. Cut through the steel, does not seem to be hollow, cuts more than just steel. Cut it all the way around the pipe, whack it with the sledge, and find out why it was hard to cut: