Error when deleting a task or a sub-task

I am getting an error when I try to delete a task or a sub-task.

I think I see the issue. I have multiple instance of the field Rank list in the Custom field area. Is there a way safe way to remove all but one instance of the field Rank?

com.atlassian.greenhopper.manager.lexorank.LexoRankIntegrityException: Expected exactly 2 rows; the maximum marker row and the lowest ranked row for rank field[id=10100]

com.atlassian.greenhopper.manager.lexorank.LexoRankIntegrityException: Expected exactly 2 rows; the maximum marker row and the lowest ranked row for rank field[id=10100]
at com.atlassian.greenhopper.manager.lexorank.LexoRankDaoImpl.getMaximumMarkerRowAndPreviousRow(LexoRankDaoImpl.java:399) [?:?]
at