To amend for this, you will basically delete the entire Schedule C from your return. The k-1 you'll produce when you prepare the S Corp return will be entered under the Investments section as a Business Investment.
Here's how to prepare an amended return but, don't do this until you have the k-1 ready and have received the refund for your original return. Amended returns are filed by mail and it takes the IRS 12-16 weeks to process them.
https://ttlc.intuit.com/questions/1894381-how-to-amend-change-or-correct-a-return-you-already-filed#
