You can only deduct it on Schedule A for Itemized Deductions.
Self-employed health insurance deduction goes on Form 1040 Schedule 1 line 29, as long as the expense is not greater than your net self-employment income. If it does exceed your net self-employment income it gets split automatically. An amount equal to your net self-employment income goes on Form 1040 Schedule 1 line 29, and the remainder gets added in to medical expenses on Schedule A.