Ability to remove termination date on an employee's record

Login: partner
Plan Effective Date: 01/01/2017
Consider Plan 1 with existing termination date on Employee Plan Termination Page as 12/31/2017
Now, change the Employee Plan termination Date lesser than Effective Date: 12/31/2016
Validation Popup for Date should be equal to greater than Effective Date > OK
Now, previous date ie. 01/01/2017 is removed.
Initially with previous implementation it should be removed. But now with this enhancement, we need to retain it.