Hmm, depends on the mood I'm in...
If I'm not in a particularly mischievous mood I'd probably turn my foot over and peel the little cat off and ask if it's okay. I'd also probably try to restore her to third dimensional life in the most basic way you can; taking a deep breath and blowing into their body to inflate them back to normal. Being so tiny however, this could backfire resulting in the tiny cat inflating so rapidly that they pop before I even realize what had happened. Kitty confetti anyone? If I DID manage to restore them to three dimensions I'd probably plop them in the shallow end of my cleavage and ferry them around for the day so no one else stepped on them or turned them into creamed cat π
If I AM in a mischievous mood, or I get the feeling that the tiny cat enjoys some rough play, I'd probably stomp on that foot wherever I went as well as dragging it and scraping it on the ground. I'd really grind the tiny cat in until they were little more than a stain on my sole. I'd also not wash my feet for as long as I could manage, that could get a bit gross, but it'd keep the little kitty stain in place so it could continue to be trod on for a few more days at the very least π