Hi,
the API is sometimes using HTTP Delete and payload.
https://www.adobe.io/creative-cloud-libraries/docs/api/#operation/deleteLibraryElements
https://www.adobe.io/creative-cloud-libraries/docs/api/#operation/archiveLibraryElements
Only the latest Http Frameworks support sending a payload using HTTP Delete. For example , the Apache HttpClient 4.x which is shipped with AEM doesn’t support payload for Http Delete.
Instead I would suggest to use query parameter which accept multiple values for the parameter elements.