Revert (reverse) \numberwithin effect

How can I revert the action of `\numberwithin{mycounter}{section}` so that `mycounter` does not reset with a new section?

Example: (This is not exactly my case but this is easy to understand.) I would like to have `equation` numbered within a section in the first part of the document, so I use `\numberwithin{equation}{section}`. But in the next part to number it directly. Like

``````Section 1
equation (1.1)
equation (1.2)
Section 2
equation (2.1)
equation (2.2)
equation (2.3)
\SomeCommandToPutHere{equation}
Section 3
equation (1)
equation (2)
equation (3)
``````
-
– lockstep Jan 25 '12 at 22:21

The package `chngcntr` does exactly that:
``````\counterwithin{equation}{section}
Thanks, master! Just a note, the macro `\counterwithout` kills the effect of both `\numberwithin` and `\counterwithin`, which is terrific! – yo' Jan 25 '12 at 21:29
Either use `\numberwithin` or `\counterwithin`, not both. – egreg Jan 25 '12 at 21:31
... and what should I do if some package uses `\numberwithin` itself without giving me a chance to prevent it? And to the case, I was thinking about putting `\let\numberwithin\counterwithin` after loading both `amsmath` and `chngcntr`. – yo' Jan 25 '12 at 21:38
The difference between `\numberwithin` and `\counterwithin` is that the former does a global redefinition, it shouldn't be a problem if `\numberwithin` is used only in the preamble. – egreg Jan 25 '12 at 21:45