MyBB Community Forums

1. How do I stop the .htaccess restriction? (Im not good with html ._.)
2. Is there another way to close the forum when upgrading a forum?

you can close from the admin panel (admin panel --> configuration --> settings --> Board Online / Offline)

you can follow this response for .htaccess method

The above .htaccess method has a drawback to it. Users can still browse the install directory and there is a small risk that they can mess up the upgrade. I think restricting the IP is a better idea. Create a single file named .htaccess with the following code:

order deny,allow  
deny from all  
allow from 127.0.0.1

Replace 127.0.0.1 with your IP address and upload it to the root of your MyBB installation. This means only you will be able to access the forum. No-one else will. After you're done upgrading, you should delete the .htaccess file.