To ignore errors when running the cleanup for a particular project, set the failOnError property to false.
<build> [...] <plugin> <artifactId>maven-clean-plugin</artifactId> <version>2.6.1</version> <configuration> <failOnError>false</failOnError> </configuration> </plugin> [...] </build>
You can also ignore them via command line by executing the following command:
mvn clean -Dmaven.clean.failOnError=false