NEC Option A - Contractor's Risk Register

The Works Information stated that all Contaminated Soil excavated needs to be removed from site. The Contractor priced a specific allowance within his risk register at Tender Award for this element.
The Contractor has now been instructed to leave all Contaminated Soil on site by the Employer. Under Option A lump sum, can the risk allowance be deducted by the Employer ?

The Works Information has been changed and as such the matter is a compensation event (I have assumed that the Contractor did not instigate the change). The financial assessment of the compensation event is the change in Defined Cost + Fee as a consequence of the compensation event, it is not the deletion of the sum in the Activity Schedule unless the PM and Contractor agree to that. The assessment will change the Prices +/-.