A=SparseArray[
{
{1,1} -> r[{1,2},{4,5}], {1,2} -> r[{3},{6}],
{2,1} -> r[{7,8}], {2,2} -> r[{9}]
},
{2,2}
]

A // MatrixForm

SparseArray[{{1,1}->zoom[7],{2,2}->2,{3,3}->3,{1,3}->4}] // MatrixForm

Flatten[A]

Flatten[A] // Normal

Delete[A, 1] // Normal

Drop[A, {1}] // Normal

Drop[A, {}, {2}] // Normal

A[[2,2]]=0

A // MatrixForm

A // ArrayRules