you sold the investment. the 1099-B shows your original cost which is no longer valid. so from the sales schedule provided by with the k-1 you need to change the cost that was imported or entered originally to the cost calculated from the sales schedule.
I recommend not using the k-1 to report all the sale info. (the sales proceeds will end up in the wrong part of form 8949 - as type c - transaction not reported to IRS so the IRS computers might not match the 1099-B reported proceeds with those reported on schedule d - types a,b,d, and e causing you to get a notice and having to explain) My way only then the sales info you enter on the k-1 sales schedule is just any ordinary income reported on the sales schedule on both the proceeds line and the ordinary income line. cost is $0. this will flow the ordinary income to form 4797 line 10
