You can declare profits below 6% / 8% as the case may be but now you need to comply eith Sec 44AA (Maintenance of Books of Accounts) and Sec 44AB (Tax Audit)
Below 8% means how much ? If turnover is in non-cash mode, you need to declare 6% profit minimum. Below this, don't file under 44AD. File ITR3 with PandL , Balance sheet with whatever actual profit figure. And note that there is no audit requirement as turnover is below 1 CR