ITC CLAIM BY MISTAKE

Actually it was my 1st time and i have only 1 sale in the month of Oct 18 and by mistaly i clam itc of 3000 rs n dnt so any outward supply, but that 3000 Rs is came to my electronic lesur instead of paying that 3000 rs. and yes i submitted my gstr1 correctly so now what i have to do now. coz i dont have any itc in that month. so now how can i correct my mistake?