In Administration >Skills Hierarchy, the application does not allow deletion of a record. If you want to wipe out all skills, and any resource associations, can you do this via the backend? To inactivate all skills causes too much unnecessary data.
Release : Any
Database updates to remove skills are not supported. There is an option to remove skills using XOG though. For the steps, see: Delete Skill definitions using XOG
The reason there isn't a delete button on the Administration side is that the Skills may be in use by resources or roles. Using the steps in the KB will allow you to remove those associations to then use a XOG to delete the skills.