Tapping on Maintenance will slide out the Maintenance drawer. As of Photosmith for iPad version 3.1, you may Purge All Unused Keywords in the Photosmith catalog. Tapping the Purge Unused Keywords button will remove all keywords in the Photosmith catalog that are not currently assigned to any photos.
Note: You may delete individual keywords by initiating the Keywords Editing drawers, and left-swiping on a keyword. This procedure is discussed in detail in the Adding, Editing and Deleting Keywords in Section 3.4.2.