Ehcp help ??

Hello , I have  2 autistic sons one of which has just turned 18 and has now decided he wants to leave college .  This is due to 1 lesson , an hour a week that causes him huge anxiety! Due to him not liking this lesson and teacher he gets very stressed!  He has an ehcp and I've spoken to college senco,  to be honest is not very helpful. My son has just given  up his maths gcse lessons as he has taken the exam twice and failed. That was also causing alot of anxiety so after a long process and lots of emails being sent and him being absent from college , they agreed to let him drop maths gcse. the senco has told me he is not allowed to drop this specific lesson!  All I want is for my 18 year old autistic son to have a bit of normality in his life , by attending college, without the pressure and anxiety.  He never leaves the house unless he goes to college , the only  friends he has are  a couple at college , but doesn't interact outside of college. He has grey hair due to him never leaving the house and getting any sun light, he also has arfid which is a eating disorder, and right hemiplegia,  and is due to have botox therapy to help his walking  . Not attending college is detrimental to his health socially,  and physically also academically!  The  worst possible scenario is him leaving , and wasting his life away ! Could anyone advise me if an ehcp could be ammended for him to get this one lesson removed? As I said college not very helpful...... so be grateful  for anyone who knows anything regarding this matter Pray