To publish a snapshot, simply run:
If you experience a HTTP 401 error during deployment, make sure your settings.xml is correctly configured and you can log in to https://oss.sonatype.org using the server username/password. See this blog for more details in troubleshooting 401 errors during deployment.
Don't worry about deploying too many snapshots so server disk will be overloaded. Nexus server has a scheduled task running weekly for cleaning up old snapshots. Snapshots older than 15 days will be deleted while a 5 minimum will always be kept. If a version is released, then all snapshots of this version will be removed.
If you want to selectively delete some snapshots, you will need log in to https://oss.sonatype.org using the same credentials you used to sign up for access to the Sonatype JIRA, go to the Repositories page and browse the Snapshots repository. In the repository tree view, right click on the node you want to delete and select Delete, just like this: