@gregs , Spray bottle and water. Warm water helps but it doesn't stay warm long.
Soak it and let it sit. Soak it and let it sit. You're on concrete it will be fine. When the remaining paper and glue starts to soften, then work on removal. You may need to go back and soak some more on the spots that didn't penetrate well. I've used sawzall scraper blades with decent luck. SDS scraper blades are spendy and they work too. They don't let you flex the blade as much so there is more fine cleaning afterward. After removing the main material, I use an angle grinder with wire wheel to tear off the last bits.
I've done a few of these floor remodels on my own properties. There's no quick shortcut if you want to do it right. It's messy and slow to do it right.
It is the perfect way to reinforce the mantra,
"Do it Right, Do it Once".
During the process you will play the mental game of figuring out how to make sure you never have to do that again.
It may sound like a lot of work and it is. In my case it has been worse because some other doofus took the shortcut approach. I've had rooms with five layers. The bottom layers are usually in the best shape. The additional top layers just don't lay down well and hold up. Simply adding layers is a setup for redoing the floor quicker.