When you originally input the information relating to the sale and purchase of your securities, you may have inadvertently reported the sale as being for "Qualified Small Business Corporation Shares" (that may be eligible for the capital gains deduction) instead of reporting the sale of the securities as being for "stocks, bonds, ..." (that are not eligible for the capital gains deduction). If so, change the reporting field from section 1 of the Schedule 3 in your return to section 3 of the Schedule 3 in your return and that should remove the capital gain deduction being claimed.
When you originally input the information relating to the sale and purchase of your securities, you may have inadvertently reported the sale as being for "Qualified Small Business Corporation Shares" (that may be eligible for the capital gains deduction) instead of reporting the sale of the securities as being for "stocks, bonds, ..." (that are not eligible for the capital gains deduction). If so, change the reporting field from section 1 of the Schedule 3 in your return to section 3 of the Schedule 3 in your return and that should remove the capital gain deduction being claimed.