Hi
Not sure why there isn't action for removing artifact from package (You can raise ER for adding this action) but this can be done using REST calls as temporary solution.
In order to remove artifact from package you need both artifact and package ID's , while package ID is built in parameter the artifact ID can retrive in two actions
1.REST call http://localhost:8080/datamanagement/a/api/v3/artifact-version-details while artifact info in the body (This should be post method)
2.Use "Json - Extract properties from a Json object" action to get the artifact ID from the REST output
3.Once you have Package and Artifact IDs use the following REST to remove the artifact from package: http://localhost:8080/datamanagement/a/artifact_packages/packageID/artifact_versions/ArtifactID (e.g http://localhost:8080/datamanagement/a/artifact_packages/266/artifact_versions/2889 , this should be delete method
Thanks
Jacky