Yes, its completely okay to leave maths in grade 11 if you wan to persue law in future. Especially if you are aiming fo 5 years inegrated law courses like ; BA LLB, BBA LLB,etc after 12th. Law enterance exams (like CLAT, AILET, SLAT, MHCET law) do not require maths at an advanced level. Most of them include basic quantitative aptitude, upto class 10 level only. I hope this will help you out.