4 HDD -> 3 HDD Raid 5 migration possible?

I’m currently using 4 x 4 TB HDD in Raid 5 setup on PR4100. I am retiring this unit as a backup NaS and want to take out one of the drive (for my new NaS).

I do know that by taking one drive out, RAID 5 will continue to work at reduced performance while keeping 12 TB space and no data redundancy.

So is there a way to convert back into 3 HDD Raid 5 setup (8TB space)? Is this kind of migration supported in OS5?

My data is only around 6TB at the moment so space shouldn’t be an issue.

There are a couple of points.

1- There is no way to reduce the number of the drives in RAID array.
2- Removing a drive will cause degraded mode on your RAID, and if anything happens to the second drive, the data will be gone.
3- Only solution: a) Take backup from data b) Recreate a new RAID array using 3 drives. c) Restore Data back to the device.