Put the following in the projects that you want checkstyle disabled for:
<project>
...
<properties>
...
<checkstyle.skip>true</checkstyle.skip>
...
</properties>
...
</project>
Checkstyle will still run, but will perform a no-op...
That is unless you override the default binding of maven-checkstyle-plugin's skip
parameter in which case you could achieve the same effect with the following in the specific project
<project>
...
<build>
...
<plugins>
...
<plugin>
<artifactId>maven-checkstyle-plugin</artifactId>
<configuration>
<skip>true</skip>
</configuration>
</plugin>
...
</plugins>
...
</build>
...
</project>
Unless of course you have overridden the skip
parameter within an execution... but if you know what that is you also know the solution and would not be asking this question ;-)