It sounds like your DH has already committed to the idea of homeschooling next year. Have you?

The answer to that question should answer the original one... if you're committed to homeschooling next year, then there's no sense in prolonging the agony for the whole family, so yes, pull him out now. If you haven't committed to it, then no, you need to have him finish this school year so promoting to 3rd grade is an option for the next.