Madame Marissa did not know this guy that well. He went ahead to spank her on the ass and she did not like it. He was not known to her in that way and she had to make it clear that it was not right to do what he had done. So she hand trampled him with her high heels so that the pain would make him never do that again.
Madame Marissa is a perfectionist and this guy did not know it. She had given him some work to do for her but he did a shoddy job of it and she had to show him that it was unacceptable to her. So the mistress used her high heel boots to trample his hands. She did it on the keyboard where he was playing games instead of doing her work.