Delete a registered user.
-(BOOL)deleteUser:(NSString*)userName password:(NSString*)passWord
        error:(NSError**)error;
  SMPClientConnection* clientConn = [SMPClientConnectioninitializeWithAppID:@"<application_id>"
domain:@"default"secConfiguration:@"<security_configuration"];
[clientConn setConnectionProfileWithHost:@"<server_host>" port:@"<server_port>"
farm:nil relayServerUrlTemplate:nil enableHTTP:YES];
NSError* error = nil;
SMPUserManager* userManager = [SMPUserManager initializeWithConnection:clientConn];
[userManager registerUser:@"<GWUsername>" password:@"<GWPassword>" error:&error isSyncFlag:NO];
//..
//..
//..       
if([userManager deleteUser:@"supuser" password:@"s3puser" error:&errors])   
{ 
    NSLog(@"supuser deleted...");
}