Project cannot be deleted by rest call without specifying team. In the past, there could be repositories which weren't assigned to any org. units but in current implementation, it is not possible. That might be a reason why the command does not work.

Server log:

10:11:17,813 ERROR [org.guvnor.rest.backend.cmd.AbstractJobCommand] (testadmin) DeleteProjectRequest [1507623077805-1] failed because of thrown ContextNotActiveException: WELD-001303: No active contexts for scope type javax.enterprise.context.RequestScoped: org.jboss.weld.context.ContextNotActiveException: WELD-001303: No active contexts for scope type javax.enterprise.context.RequestScoped
at org.jboss.weld.manager.BeanManagerImpl.getContext(BeanManagerImpl.java:689)
at org.jboss.weld.bean.ContextualInstanceStrategy$DefaultContextualInstanceStrategy.getIfExists(ContextualInstanceStrategy.java:90)
at org.jboss.weld.bean.ContextualInstanceStrategy$CachingContextualInstanceStrategy.getIfExists(ContextualInstanceStrategy.java:165)
at org.jboss.weld.bean.ContextualInstance.getIfExists(ContextualInstance.java:63)
at org.jboss.weld.bean.proxy.ContextBeanInstance.getInstance(ContextBeanInstance.java:83)
at org.jboss.weld.bean.proxy.ProxyMethodHandler.invoke(ProxyMethodHandler.java:99)
at org.uberfire.rpc.SessionInfo$1143114360$Proxy$_$$_WeldClientProxy.getIdentity(Unknown Source)
at org.guvnor.structure.backend.organizationalunit.OrganizationalUnitServiceImpl.getOrganizationalUnits(OrganizationalUnitServiceImpl.java:126)
at org.guvnor.structure.backend.organizationalunit.OrganizationalUnitServiceImpl$Proxy$_$$_WeldClientProxy.getOrganizationalUnits(Unknown Source)
at org.guvnor.common.services.project.backend.server.ProjectServiceImpl.getAllProjects(ProjectServiceImpl.java:77)
at org.guvnor.common.services.project.backend.server.ProjectServiceImpl.resolveProject(ProjectServiceImpl.java:155)
at org.guvnor.rest.backend.JobRequestHelper.deleteProject(JobRequestHelper.java:204)
at org.guvnor.rest.backend.JobRequestHelper$Proxy$_$$_WeldClientProxy.deleteProject(Unknown Source)
at org.guvnor.rest.backend.cmd.DeleteProjectCmd.internalExecute(DeleteProjectCmd.java:44)
at org.guvnor.rest.backend.cmd.AbstractJobCommand.run(AbstractJobCommand.java:93)
at org.uberfire.backend.server.cdi.workspace.WorkspaceExecutorService.lambda$generateRunnable$0(WorkspaceExecutorService.java:135)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)