typeset -a a
a=(1 2 3 4)

typeset -A A
A=([one]=1 [two]=2 [three]=3 [four]=4)

unset 'a[0]'
typeset -p a

scalar=abcd
echo ${scalar[0]}

unset 'scalar[0]'
echo ${scalar-unset}

unset 'a[@]'
typeset -p a

unset 'A[@]'
typeset -p A

typeset -a a
a=(1 2 3 4)
typeset -A A
A=([one]=1 [two]=2 [three]=3 [four]=4)

# supported, recommended way to unset all array elements
a=()
typeset -p a
A=()
typeset -p A

declare -a foo
declare foo='(1 2 3)'
declare foo[1]='(4 5 6)'

declare -p foo