Every state is different with regards to homeschool. I withdrew my son from public school after spending an entire weekend researching homeschool programs in my area. Check to see how many missed days from school your child can have before they are considered truant. Research EVERYTHING. Enroll in a homeschool program and they will help you with the legal angle of proper procedure.
My own experience... I removed my child on a Friday. Researched all weekend long. My child was allowed to miss 3 days of school before a doctor's notice was needed. He was enrolled in a homeschool program by Tuesday and with all paperwork in hand, we withdrew him the very next Friday. And we haven't regretted our decision for a single minute.