I assume you mean Cetol that has dripped and dried? Wet Cetol comes off easily with a rag dipped in mineral spirits. Dry Cetol, especially if it dropped into your non-skid, is a real challenge. The previous owner of my previous boat was not a careful painter and dropped some Cetol here and there on the deck. After trying careful scraping, fiberglass paint remover, etc., I gave up after only limited success. But here is what worked for me: I took an artist's small pointed brush and painted the Cetol spots with white topside paint. Worked great....
