I have a linux ( CentOS ) server that has 2 hard drives, and it configure by software raid1,
Now I need to un-raid hard drives, and use both of them. How can I Un-raid them ? ( I just has SSH access )
While the filesystem type will be "linux-raid" rather than "linux" you can still break the mirror and reformat the 2nd drive. Then you can either copy all the data across and reformat the 1st drive too, or run the raid drive in degraded mode forever. I'm not sure there's a performance hit doing this.
You'll want to use mdadm to break the mirror, by marking one of the disks as failed. Then format it. Remember to reset the bootloader or it'll still try to boot into the raid partition, rather than your new plain partition.
A quick google says that you can shrink your raid array, so you could keep a small RAID1 array, and then use the remainder of the 2 drives as 2 new partitions.
Your only solution is to dump the content somewhere else, destroy the RAID array and reinstall your OS. You cannot "unraid" an array because it destroys the structure underlying your filesystem.