Just remember there is three versions of this expanding foam, it is important around windows and doors to use the lower expansion product and not bow the frames, also don't over use it, let the stuff fill the gaps before you spray too much of it. Otherwise you have a large mess to clean up. Helps to put oil on your hands before using. I think I remember lacquer thinner cleans it up, but it burns on cuts really bad.
Where are you using this? This is meant for water tight applications, such as shower walls. Don't recommend it for floors as they need to breath, unless you are talking wood underlayment?
If you hand chisel this up it will take 5 times longer, air or rotary hammer chisel is the only way to go. Plus you can get all the thin set up.....over concrete you don't need to a water guard.
Wax marker, furniture touch up stick.
You can rent a chipping hammer, will be done in 1/2 hour, saving time and money, put a mask on and cover that door way with plastic. Wish I could lend you my Bosch rotary hammer...with a wide blade.