No you don't need to remove any files... backup your database, download the changed files package from 1.6.1 release announcement blog post, upload it so the files inside overwrite your current files, and go to yoursite.com/install/upgrade.php and choose 1.6.0 from the list.
so, I should remove only files that available in package, and upload them in new package.
Thanks a lot
No, you don't need to remove them, you just need to upload the new files, and they will automatically replace the old files.
another question.
It is need to download config.php and setting.php file and upload them after upload other files??
Uploading the new files won't do anything to those files, they'll be left as they are.
I can not get a backup of my database.
is it need really?
Well, it's very unlikely anything will go wrong with this upgrade but it's always a good idea to have one anyway... you can take one via phpMyAdmin if you can't take from from the MyBB ACP.
I know...
But when I click on my database name in phpmyadmin do'nt show any page
You'd need to ask your host about that, that's not something we can do anything about. If you delete the ./install/ folder you'll be able to take a backup in the MyBB ACP, then you'll just need to upload the ./install/ folder again, and run the upgrade script.
or only upload this files in this folder: http://www.mybb.com/download/128