Could Eraserhead delete all All for One quirks at once? All for One is this powerful villain, who is almost unstoppable because he has and can use many quirks. Is there any reason why they never used Eraserhead to stop him by blocking all his quirks? Is this just a missing point in the plot or is there any limit to Eraserhead abilities or any quirk to All for One that makes him inmune to Eraserhead abilities?
This is mostly speculation, and incredibly hypothetical. With the evidence given, All For One (A4O) by itself is an activation based or transformation type quirk, and that activation can steal, grant/transfer quirks. However, the quirks that are stolen may or may not be used only when A4O is activated.

Erasure, another "Activation" quirk, can disable the quirk factor of any person caught in range. Thus those with Emitter and Transformation based quirks are disabled, but mutant-type quirks lose their functionality.

As far was we can tell the only time Erasure was used on a person with more than one quirk was on Deku in the skills assessment test (One For All is considered as multi-quirk; the stockpile, and the transfer quirks). However, since Deku only used the "superhuman strength" quirk, we don't know if there were other quirks that have been stockpiled. Also, whether or not a person wielding One For All can use Superhuman Strength + another quirk. This can end in one of two ways.

Conjecture 1: If the root of all quirk based power is rooted in the quirk factor, it is possible for Aizawa to disable A4O and all the stolen quirks  with the Erasure Quirk.

Conjecture 2: If the A4O quirk does not need to be activated to use stolen quirks, AND stolen quirks are separate from the Quirk factor of A4O; if and only if each quirk has its own Quirk Factor and Aizawa can disable only one Quirk factor within one person; then A4O will not be disabled by the Erasure Quirk.