DELETE FROM `table` WHERE `field`= nothing

DELETE FROM `table` WHERE `field`= nothing

How do I delete all rows that have a field called A that are blank.
Lets say I have a table that looks like the following.
|ID |A |B |C
|1 |Data|Data|Data
|2 | |Data|Data
|3 |Data| |Data
|4 | | |
So in the above example row 2 and 4 would be removed because there isn't
anything stored in them?
How can I do this I'm doing I'm thinking something along the lines of the
following.
DELETE FROM `table` WHERE `A`= ''
Is that that correct?