To update Categories for your Staff, either to Add New, Edit existing categories or remove one, first you need to go to Account in the Left-Hand menu bar, and click on Settings.
Note! You must have an 'Admin' role to be able to do this.
In the Account Settings' page, click on 'Edit'. The next page is quite long so you need to scroll down 'till you reach near the end of the middle part, and you'll see the sections: Competences, Qualifications, KPI, Compliance and others. This is where you can enter the Categories you wish to add or find those you need to edit. When adding, choose which section should it be under, and once done click on Save.
To check/verify, you can look up Staff's Documents page, and try to click on Category selection list, the new one added or the newly updated category should be shown here.