How to remove associated contact from call using Rest API

HI Team ,

 I created call with contact and tried to remove the contact from call during updation using Rest API . But no luck to remove the contact .

PUT  <domain>/rest//Calls/<call_Id>


It Return 200 OK . But Contact is not removed in sugar CRM. I tried to send a payload with empty string / NULL / empty Object to contacts , result was 400 Bad Request .

Can you help me to remove contact from call using rest api ?