When you first create a plugin (at least with custom maven coordinates), it needs manual approval from a Gradle team member. After this, any new version that you publish is immediately available on the portal.
As for deleting a particular version of the plugin, you can do this yourself from the plugin page. Make sure you are logged in with the user who owns the plugin, select the version from the drop-down and press the delete button.
Lastly, it is not (yet) possible to update the description or tags for a plugin. But you can request a change using the help page and a Gradle team member will hopefully be kind enough to fix it. See here for a comment about this issue.