code: @Delete("/tokens/{appId}")
      public CompletableFuture<Token> deleteToken(ServiceRequestContext ctx,
                                                  @Param("appId") String appId,
                                                  Author author, User loginUser) {
          return getTokenOrRespondForbidden(ctx, appId, loginUser).thenCompose(
                  token -> mds.destroyToken(author, appId)
                              .thenApply(unused -> token.withoutSecret()));
      }
docs: DELETE /tokens/{appId}
  
  <p>Deletes a token of the specified ID then returns it.