There is no tax deduction or credit for repayment of previously reported income unless you repaid more than $3,000 in one year. If you repaid $6,500 over the course of 4 years, you probably did not repay more than $3,000 in any one year. In that case you do not get any tax adjustment, so there is nothing for you to do.
If you did repay more than $3,000 in a single year, you would claim the deduction or credit on your tax return for that year. If you already filed a tax return for the year that you repaid more than $3,000 you would have to file an amended return for that year to claim the deduction or credit.
In any case, you do not actually enter the 1099-G forms in your tax return.
