I did not make enough business income to contribute the maximum of $54,000. Can I withdraw the excess before taxes are due 4/17/18?
Yes, you can withdraw the excess before taxes are due. "Employees who withdraw the excess contribution (plus earnings) before the due date for their federal return, including extensions, will avoid the 6% excise tax imposed on excess SEP contributions in an IRA."
Click the IRS link below for more information.