How can I convert from RAID 1 to RAID 0

[harmonyp]

I have 6 disk in total and both /dev/sda and /dev/sdb are in RAID 1 whist the other 4 disks are part of a ZFS RAID 10.

How would I go about removing the RAID 1 on /dev/sda and /dev/sdb to free up /dev/sdb - If possible without a reboot?

cat /proc/mdstat

Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10]
md4 : active raid1 sdb4[0] sda4[1]
      405772096 blocks super 1.2 [2/2] [UU]
      bitmap: 0/4 pages [0KB], 65536KB chunk


md2 : active raid1 sdb2[1] sda2[0]
      41910272 blocks super 1.2 [2/2] [UU]


unused devices: <none>

vgdisplay

--- Volume group ---
  VG Name               vg
  System ID
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  7
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                3
  Open LV               3
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               386.97 GiB
  PE Size               4.00 MiB
  Total PE              99065
  Alloc PE / Size       99065 / 386.97 GiB
  Free  PE / Size       0 / 0
  VG UUID               e2YzU3-HzQe-DIqH-HGNr-tFqc-cWO1-K92uOR