If you have an existing mirror or trans metadevice, you can use the metarename -x command to remove the mirror or trans metadevice and keep data on an underlying metadevice. For a trans metadevice, as long as the master device is a metadevice (stripe/concat, mirror, or RAID5 metadevice), you keep data on that metadevice.
When you use metarename -x as part of this process, the mount point of the file system remains the same.