para o bit resize2fs, é assim:
e2fsck -f /dev/myvg/lvtest
resize2fs /dev/myvg/lvtest 96M #always a bit smaller than the LV
### then the rest as above
lvresize -l 100M /dev/myvg/lvtest
vgreduce myvg /dev/sdX
###then regrow that to fit the volume perfectly
lvresize -l 100% /dev/myvg/lvtest
resize2fs /dev/myvg/lvtest
Espero que você esteja no ext2 / 3/4. Se no XFS, você precisa ser criativo!