This method deletes a reward assignment for a particular reward.
The access token received from the authorization server in the OAuth 2.0 flow.
A unique reward ID.
"rew_2erjvECLs92GYzKbak3QkyTV"
A unique reward assignment ID.
"rewa_m9hEAu10KsPcLhGXiHG85aY0"
Returns no content if deletion is successful.