Actual Start / End Date - can they be clear on a test execution?

I did an update using Zephyr Server API (v1) with a python program and the test execution it is showing the Actual Start / End Date when the update was did, the test execution status is not executed (no one have started the execution)... I need to clear / delete the values in fields Actual Start / End Date without create a new test execution... is it possible?