I just did this with Charles Schwab.
An easy solution is to
1. Open your existing file
2. Go to File in the upper left hand corner
3. Scroll down to "remove imported data"
4. A list pops up of all the forms you have imported
5. Click the items you want to correct (remove)
6 Go back to income and dividends and you should be able to log into your Schwab account and re-import the 1099 Corrected from Schwab.
Easy peasy!
