My son decided to try his hand at art by taking a blue spray paint can and spraying one of the concrete pillars on the front porch of the house. I went to the local Home Depot and the lady suggested Licquer thinner, spraying or wiping it on and then scrubbing it off. I've tried a variation of that where I spray the thinner on, and noticed that a lot of it comes off instantly if the spray is a hard blast directly on it. Scrubbing it seems to only move the "loose" blue paint around creating smudge type marks.
Here is a link to how it looks before my attempt to clean it: https://photos.app.goo.gl/SLuTo0H8ghDf1P3H2
Here is a link to how it looks after my attempt to clean it: https://photos.app.goo.gl/P3ra4R99azZWPcJ33
I have more of the licquer thinner left but I don't think it's going to do any more of a job then what you see. Any advice is appreciated as this is a rental home so I really need to take care of this and soon.
On another note my son also spray painted some yellow paint on the back steps (wooden). Should I try the same stuff?