3811200 - Warning: "List item XXX was in use by the Request Authorized Approver hierarchy. Deleting this list item may result in some employees being assigned to an inactive group. Run an employee import with updated list item values to reassign employees.."

We have noticed the following warning message on one of our list imports:
"List item XXX was in use by the Request Authorized Approver hierarchy. Deleting this list item may result in some employees being assigned to an inactive group. Run an employee import with updated list item values to reassign employees to valid groups")

We have checked and found found that no approver is maintained for this cost center in Concur production system. 
In this case why do we receive these warnings?

List Import Warning Message , KBA , CON-EXP-ADM-LIS , List Management , Problem