[JIRAALIGN-801] Can't delete dates on Objective once dates are target dates, ask dates, and completion dates are select.

Issue: Dates can't be deleted and don't have the reset and lock button PM said we should allow users to delete each individual date after it's saved without having to click reset. This should be applied to all work items. 

STR:
Add all three dates ask, start, and completion and save on an objective
Then try and delete.

ER:
Should be able to manually delete each one after save. (For all work items)

Also, there is no reset or lock option please add

AR:
Can't delete