In the Workstation prior versions of Devtest , when selecting the DELETE method in the REST step, the Content tab is greyed out.
Selecting a different method like GET, POST or PUT allows the Content to be specified.
10.6 & up
The REST step is used when testing REST applications to send and receive HTTP(S) requests, including GET and POST parameters.
The following methods are supported:
GET
POST
DELETE
PUT
HEAD
PATCH
OPTIONS
https://techdocs.broadcom.com/us/en/ca-enterprise-software/devops/devtest-solutions/10-6/reference/test-step-descriptions/web-web-services-steps/rest-step.html