The line graph of a graph G has one node per each edge of G, two of them being adjacent only when the corresponding edges have a node of G in common. In this work, we consider the problem of finding the minimum number of edges to delete so that the resulting graph is a line graph, which presents an interesting application in haplotyping of diploid organisms. We propose an Integer Linear Programming formulation for this problem. We compare our approach with the only other existing formulation for the problem and explore the possibility of combining both of them. Finally, we present a computational study to compare the different approaches proposed.