You are just taking them off your 1099B in theory. To be technically 1099b income is reported on schedule D. You are taking them off schedule D by listing them on you schedule C then carrying that number over to your schedule D as a negative number. (or a lost trade)
You just need to list the expenses on schedule C because that is the only way the goverenment gives people to list their expenses. List them on schedule C. Make it a 0 when you are done. Either manually (if not using turbotax) or make a expense that is negative 10k to make the grand total 0 on schedule C.
