[jester911]

If the wall is built with mortar it really won't be that hard.
Rent a medium size chipping hammer with points and chisels.

Chisel out two or three brick/block. Once you have a few removed use the chisel in the mortar joints to break loose the remainder. There may be reinforcing wire in some of the mortar joints. You may need to cut or saw this wire.
Once you have a few bricks removed don't try to chisel on bricks, only the joints.

You will find they will pop right out. The first few bricks will
be the hardest but trust me it won't be bad after that.