It depends on what you are going to replace it with!
As Ron J. said, if you are just going to replace it with carpeting, I think the scrape method should be just fine. (less mess)
But if you are going to use something that needs to be installed on a clean dry suface, you may want to consider a floor sander?
There may be a solvent out there that will do the job but, I do not know of one by name.
Are you planning to glue this pad to the floor?
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