To remove the 1099 you started to enter, return to > Federal > Wages & Income, select the option to view all income types. Depending on the type of 1099 you started to enter, go back into the appropriate section and go through the screens until you get to the 1099 and delete it.
Alternatively, you can go to > Tax Tools > Tools > Delete a form > and select the form you would like to delete from the list.
