After I hot wax my board and let it cool, I begin to scrape it with a plastic scraper and the wax sometimes doesn't peel off, it would start to crack off.
Could it be the kind of wax I use(Toko workshop wax)?
I was wondering what is the reason why this is happening, is it bad for the board or am I defeating the purpose of waxing because it is cracking?
Usually a combination of i) the type of wax, and ii) (much) too much wax. Ambient temperature/cooling speed can also be a factor.
Depending on how well you ironed the wax onto the base, it might defeat the purpose of waxing (if there is a purpose to waxing).
But it is not bad for your board (assuming that this is not happening because you are scraping off part of the base LOL).