Removing vinyl floor glue from concrete

[64 Thunderbolt]

Hey guys. I took up the vinyl flooring that was on the floor in the room I removed from my garage. As you can seen in this image I still have some glue left I need to remove. I've read various things online including pouring boiling water on it to remove it.

What is the best way to get this off? We pressure washed it and this is what we have left.

 

[The Cobbler]

a 4" razor scraper with good blades and muscle
http://www.robertsconsolidated.com/en/products.php?c=&cat=30&sub=0&prod=337

 

[LegacyIndustrial]

Diamond Grinder

 

[Armorpoxy]

We carry a mastic dissolver/softener you apply, let dwell and then easily scrape off. Eliminates the need for a grinder and reduces the labor.

https://armorpoxy.com/products/mastic-remover-1-gal-size/