First check the blv record using,

# bootlist -m normal -o

Remove the old blv record, using

# chpv -c hdisk2

# bootlist -m normal hdisk1

# bootlist -m normal hdisk2

Now unmirrorvg

# unmirrorvg rootvg hdisk2

# reducevg rootvg hdisk2

#lsvg -p rootvg

# lspv

# bootlist -m normal -o