Thanks for the valuable info. You guys simply are the best!
I went to auto store and looked for clay bar but the big bottle that says clay bar costs around $20 which I can't afford and need cos I only got few scattered white paint spots on my car hood. I instead bought the smaller one which is turtle brand and says bugs tar paintspots remover and I got it for just $3 bucks.

I put the stuff on soft cloth and rubed gently for like a minute or 2 on each spots and eventually it worked.

The remover also says something like ok for clear coats or something which I don't know what it means.

thanks guys,

btw the paint is i think to apply on walls so maybe for housepaints.