I haven't applied for an EHCP for my child as she has never been to school, won't be going in the next few years, and I don't think the LA has anything to offer her while she is being HE. However, I have a rough idea how it works.
So long as your son is not actually enrolled at the special school, you can remove him from mainstream to home ed upon demand. If he is enrolled at special school the law is different, and you must ask for LA consent to deregister and home educate. This is meant to be a formality, and consent should not be unreasonably withheld. When you withdraw your son to home educate him, the EHCP will be reviewed and the placement changed to elective home education.
For a child who is being home educated, if you argue hard and if the child has very obvious needs for LA support even while being home educated, you MAY be able to get some funding to assist with home education. Most parents don't bother trying to get that, as it is very difficult.
If you aren't trying to get funding for home ed then the EHCP remains in place but is a fairly theoretical document, detailing how the LA would support him if he were at school. You yourself don't have to meet the provisions which are described in it. The LA is obliged to maintain the EHCP so long as it is relevant. They aren't often ceased. You could ask for it to be ceased if you are sure it isn't needed, and the LA may comply with your request if they agree with you. Most parents prefer to keep the EHCP, because it will be useful if the child ever does return to school or college. Obviously it would need updating at that time, but you can skip the first hurdle of applying for the EHCP, so you'll save time and effort if you keep it ticking over.
While your son is being home educated, the LA will review the EHCP regularly and will ask for your input into it. Apparently this is a fairly pointless but harmless exercise. You should be invited to the review meetings, but you don't have to attend.