Multiple depth graph of the same track causes delete problem

1) Go to Arabidopsis thaliana > Jun 2009
2) Select TAIR 10 mRNA
3) Change load mode to whole genome.
4) Right click TAIR10 mRNA track > Make depth graph
5) Repeat the step again
6) Change one depth graph FG color
7) Now delete TAIN 10 mRNA from load mode table
8) Notice one depth graph still display after deletion