Storage pool reduction/Disk removal

[Enquiries]

Hey guys I hope you are all doing well. I need a little help with a change I want to make on my NAS

NAS: TS-653D (QTS 5.0.1.2173)

4 x 4TB disks in RAID5 (Slots 1 - 4)

Single storage pool 8.5TB unallocated

1 Thin Volume 7TB free

I would like to permanently remove the disk from slot 4 to use for another purpose. Is there a way to safely reduce the storage pool to achieve this?

[ed]

You can technically remove the last drive. But this will mean no redundancy. There is no way to change the number of drives in existing RAID from 4 to 3. You will need to delete and recreate a RAID.
You can then have RAID5 on first 3 drives. The last drive would have basic mode - running on its own.

I hope this helps.